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,* i 

Gas-Engines and 
Producer-Gas Plants 




Member of the Socilte' des Ingenieurs Civils de France, Institution of 

Mechanical Engineers, Association des Ingenieurs de 

l'Ecole des Mines du Hainaut of Brussels 


WALDEMAR B. KkB^FPEkt; - ## . * # * 

• •* # 


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* * *■> 



The Norman W. Henley Publishing Company 




0837 1 4 


• 1916 L 


Copyright, 1905, by 
The Norman W. Henlky Publishing Company 

Also, Entered at Stationers* Hall Court, London, England 

All Rights Reserved 

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Dugald Clerk, M.Inst.C.E., F.C.S. 

Mr. MATHOT, the author of this interesting work, 
is a well-known Belgian engineer, who has devoted 
himself to testing and reporting upon gas and oil 
engines, gas producers and gas plants generally for 
many years past. I have had the pleasure of knowing 
Mr. Mathot for many years, afe^!havjeL ; irVsp'eCte(f-sas- 
engines with him. I have been 'mucliitruck.-vvith the 
ability and care which he has deVotfedU<* -this 'subject. 
I know of no engineer more competent ib ideal with 
the many minute points which occur in the installation 
and running of gas and oil engines. I have read this 
book with much interest and pleasure, and I consider 
that it d^als effectively and fully with all the principal 
detail points in the installation, operation, and testing 
of these engines. I know of no work which has gone 
so fully into the details of gas-engine installation and 
up-keep. The work clearly points out all the matters 
which have to be attended to in getting the best work 


vi Preface 

from any gas-engine under the varying circumstances 
of different installations and conditions. In my view, 
the book is a most useful one, which deserves, and no 
doubt will obtain, a wide public recognition. 

Dugald Clerk. 

March, ipoj. 

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The constantly increasing use of gas-engines in the 
last decade has led to the invention of a great number 
of types, the operation and care of which necessitate 
a special practical knowledge that is not exacted by 
other motors, such as steam-engines. 

Explosion-engines, driven by illuminating-gas, pro- 
ducer-gas, oil, benzin, alcohol and the like, exact 
much more care in their operation and adjustment 
than steam-engines. Indeed, steam-engines are regu- 
larly subjected to comparatively low pressures. The 
temperature in the cylinders, moreover, is moderate. 

On the other hand, the explosion-motor is irregu- 
larly subjected to high and low pressures. The tem- 
perature of the gases at the moment of explosion is 
exceedingly high. It is consequently necessary to re- 
sort to artificial means for cooling the cylinder; and 
the manner in which this cooling is effected has a very 
great influence on the operation of the motor. If the 
cooling be effected too rapidly, the quantity of gas 
consumed is considerably increased; if the cooling be 
effected too slowly, the motor parts will quickly de- 

In order to reduce the gas consumption to a mini- 
mum, a matter which is particularly important when 



the motor is driven by street-gas, the explosive mixture 
is compressed before ignition. Only if all the parts 
are built with joints absolutely gas-tight is it possible 
to obtain this compression. The slightest leakage past 
the valves or around the piston will sensibly increase 
the consumption. 

The mixture should be exploded at the exact mo- 
ment the piston starts on its working stroke. If igni- 
tion occur too soon or too late, the result will be a 
marked diminution in the useful effect produced by 
the expansion of the gas. All ignition devices are 
composed of delicate parts, which cannot be too well 
cared for. 

It follows from what has thus far been said that the 
causes of perturbation arc more numerous in a gas than 
in a steam engine; that with a gas-engine, improper 
care will lead to a much greater increase in consump- 
tion than with a steam-engine, and will cause a waste 
in power which would hardly be appreciable in steam- 
engines, whether their joints be tight or not. 

It is the purpose of this manual to indicate the more 
elementary precautions to be taken in the care of an 
engine operating under normal conditions, and to ex- 
plain how repairs should be made to remedy the in- 
juries caused bv accidents. Engines which are of less 
than 200 horse-power and which are widely used in a 
small way will be primarily considered. In another 
work the author will discuss more powerful engines. 

Before considering the choice, installation, and oper- 
ation of a gas-engine, it will be of interest to ascertain 


the relative cost of different kinds of motive power. 
Disregarding special reasons which may favor the one 
or the other method of generating power, the net cost 
per horse-power hour will be considered in each case 
in order to show which is the least expensive method 
of generating power in ordinary circumstances. 

March, 1905. 







The Otto Cycle. — The First Period. — The Second Period. — The 
Third Period. — The Fourth Period. — Valve Mechanism.-rlgnition. 
— Incandescent Tubes. — Electric Ignition. — Electric Ignition by 
Battery and Induction-Coil. — Ignition by Magnetos. — The Piston. — 
Arrangement of the Cylinder. — The Frame. — Fly-Wheels. — Straight 
and Curved Spoke Fly-Wheels. — The Crank-Shaft. — Cams, Rollers, 
etc. — Bearings. — Steadiness. — Governors. — Vertical Engines. — 
Power of an Engine. — Automatic Starting • • . . . . 21 


Location. — Gas-Pipes. — Dry Meters. — Wet Meters. — Anti-Pulsators, 
Bags, Pressure-Regulators. — Precautions. — Air Suction. — Exhaust. 
— Legal Authorization 69 


The Foundation Materials. — Vibration. — Air Vibration, etc. — Exhaust 
Noises 87 





Running Water. — Water-Tanks. — Coolers 98 


Quality of Oils. — Types of Lubricators Ill 



General Care. — Lubrication. — Tightness of the Cylinder. — Valve- 
Regrinding. — Bearings. — Crosshead. — Governor. — Joints. — Water 
Circulation. — Adjustment 121 


Care during Operation. — Stopping the Engine 128 




Difficulties in Starting. — Faulty Compression. — Pressure of Water in 
the Cylinder. — Imperfect Ignition. — Electric Ignition by Battery or 
Magneto. — Premature Ignition. — Untimely Detonations. — Retarded 
Explosions. — Lost Motion in Moving Parts. — Overheated Bearings. 
— Overheating of the Cylinder. — Overheating of the Piston. — Smoke 
arising from the Cylinder. — Back Pressure to the Exhaust. — Sudden 
Stops 134. 





High Compression. — Cooling. — Premature Ignition. — The Govern- 
ing of Engines 153 



Street-Gas. — Composition of Producer-Gases. — Symptoms of Asphyxi- 
ation. — Gradual, Rapid Asphyxiation*. — Slow, Chronic Asphyxiation. 
— First Aid in Cases of Carbon Monoxide Poisoning. — Sylvester 
Method. — Pacini Method. — Impurities of the Gases .... 165 



Dowson Producer. — Generators. — Air- Blast. — Blowers. — Fans. — 
Compressors. — Exhausters. — Washing and Purifying. — Gas- 
Holder. — Lignite and Peat Producers. — Distilling-Producers. — Pro- 
ducers Using Wood Waste, Sawdust, and the like. — Combustion- 
Generators. — In verted. Combustion 174 



Advantages. — Qualities of Fuel. — General Arrangement. — Generator. 
— Cylindrical Body. — Refractory Lining. — Grate and Support for the 
Lining. — Ash-pit. — Charging- Box. — Slide-Valve. — Cock. — Feed- 
Hopper. — Connection of Parts. — Air Supply. — Vaporizer. — Pre- 
heaters. — Internal Vaporizers. — External Vaporizers. — Tubular Va- 
porizers. — Partition Vaporizers. — Operation of the Vaporizers. — Air- 
Heaters. — Dust-Collectors. — Cooler, Washer, Scrubber. — Purifying 
Apparatus. — Gas-Holders. — Drier. — Pipes. — Purifying-Brush. — 



Conditions of Perfect Operation of Gas-Prod ucers. — Workmanship 
and System. — Generator. — Vaporizer. — Scrubber. — Assembling the 
Plant. — Fuel. — How to Keep the Plant in Good Condition. — Care 
of the Apparatus. — Starting the Fire for the Gas-Producer. — Starting 
the Engine. — Care of the Generator during Operation. — Stoppages 
and Cleaning • 199 



Oil-Engines. — Volatile Hydrocarbon Engines. — Comparative Costs. — 
Tests of High-Speed Engines. — The Manograph. — The Continuous 
Explosion-Recorder for High-Speed Engines. — Records . . . 264 


The Duty of a Consulting Engineer. — Specifications. — Testing the 
Plant. — Explosion-Recorder for Industrial Engines. — Analysis of 
the Gases. — Witz Calorimeter. — Maintenance of Plants. — Test of 
Stockport Gas-Engine with Dowson Pressure Gas-Producer. — Test 
of a Winterthur Engine. — Test of a Winterthur Producer-Gas 
Engine. — Test of a Deutz Producer-Gas Engine and Suction Gas- 
Producer. — Test of a 200-H.P. Deutz Suction Gas-Producer and 
Engine 279 



THE ease with which a gas-engine can be installed, 
compared with a steam-engine is self-evident. In 
places where illuminating gas can be obtained and 
where less than 10 to 15 horse-power is needed, street- 
gas is ordinarily employed.* The improvements which 
have very recently been made in the construction of 
suction gas-generators, however, would seem to augur 
well for their general introduction in the near future, 
even for very small powers. 

The installation of small street-gas-engines involves 
simply the making of the necessary connections with 
gas main and the mounting of the engine on a small 

An economical steam-engine of equal pown would 
necessitate the installation of a boiler and its setting, 
the construction of a smoke-stack, and othn a< < rs 
sories, while the engine itself would requiir a In in 
base. Without exaggeration it may be assc-itnl that 
the installation of a steam-engine and of its build i<- 
quires five times as much time and trouble: ;ri tin- m 
stallation of a gas-engine of equal powci, without 
considering even the requirements imposed by '.foniij» 
the fuel (Fig. 1). Small steam-engines mounted on 

* Recent improvements made in suction fra*-pro<!u"-ri v.- ill |ii<#f,.iUy l<ml 
to the wide introduction of producer gas engines even for uimII j,»,v.m. 



their own boilers, or portable engines, the consumption 
of which is generally not economical, are not here 
taken into account. 

So far as the question of cost is concerned, we find 
that a 15 to 20 horse-power steam-engine working at 
a pressure of 90 pounds and having a speed of 60 revo- 
lutions per minute would cost about 16 ^ per cent, 
more than a 15 horse-power gas-engine, with its anti- 
pulsators and other accessories. The foundation of 
the steam-engine would likewise cost about 16^ per 
cent, more than that of the gas-engine. Furthermore 
the installation of the steam-engine would mean the 
buying of piping, of a boiler of 100 pounds pressure, 
and of firebrick, and the erection of a smoke-stack hav- 
ing a height of at least 65 feet. Beyond a little excavat- 
ing for the engine-base and the necessary piping, a 
gas-engine imposes no additional burdens. It may be 
safely accepted that the steam-engine of the power 
indicated would cost approximately 45 per cent, more 
than the gas-engine of corresponding power. 

The cost of running a 15 to 20 horse-power steam- 
engine is likewise considerably greater than that of 
running a gas-engine of the same size. Considering 
the fuel-consumption, the cost of the lubricating oil 
employed, the interest on the capital invested, the cost 
of maintenance and repair, and the salary of an engi- 
neer, it will be found that the operation of the steam- 
engine is more expensive by about 23 per cent. 

This economical advantage of the gas over the steam- 
engine holds good for higher power as well, and be- 

comes even more marked when producer-gas is used 
instead of street-gas. Comparing, for example, a 50 
horse-power steam-engine having a pressure of 90 
pounds and a speed of 60 revolutions per minute, with 
a 50 horse-power producer-gas engine, and considering 
in the case of the steam-engine the cost of a boiler of 
suitable size, foundation, firebrick, smoke-stack, etc., 
and in the case of the gas-engine the cost of the pro- 
ducer, foundation, and the like, it will be found that 
the installation of a steam-engine entails an expendi- 
ture 15 per cent, greater than in the case of the pro- 
ducer-gas engine. However, the cost of operating and 
maintaining the steam-engine of 50 horse-power will 
be 40 per cent, greater than the operation and main- 
tenance of the producer-gas engine. 

From the foregoing it follows that from 15 to 20 
up to 500 horse-power the engine driven by producer- 
gas has considerably the advantage over the steam- 
engine in first cost and maintenance. For the develop- 
ment of horse-powers greater than 500, the employment 
of compound condensing-engines and engines driven by 
superheated steam considerably reduces the consump- 
tion, and the difference in the cost of running a steam- 
and gas-engine is not so marked. Still, in the present 
state of the art, superheated steam installations entail 
considerable expense for their maintenance and repair, 
thereby lessening their practical advantages and ren- 
dering their use rather burdensome. 



Explosion- engines are of many types. Gas-en- 
gines, of the four-cycle type, such as are industrially 
employed, will here be principally considered. 

The Otto Cycle.— The term " four-cycle " motor, or 
Otto engine, has its origin in the manner in which the 
engine operates. A complete cycle comprises four dis- 
tinct periods which are diagrammatically reproduced 
in the accompanying drawings. 

The First Period. — Suction: The piston is driven 
forward, creating a vacuum in the cylinder, and simul- 
taneously drawing in a certain quantity of air and gas 
(Fig. 2). 

Fig. 2. — First cycle: Suction. 

The Second Period. — Compression: The piston re- 
turns to its initial position. All admission and exhaust 
valves are closed (Fig. 3). The mixture drawn in 
during the first period is compressed. 



The Third Period. — Explosion and Expansion: When 
the piston has reached the end of its return stroke, the 
compressed mixture is ignited. Explosion takes place 
at the dead center. The expansion of the gas drives the 
piston forward (Fig. 4). 

Fig. 3. — Second cycle: Compression. 

Fig. 4. — Third cycle: Explosion and expansion. 

The Fourth Period. — Exhaust: The piston returns 
a second time. The exhaust-valve is opened, and the 
products of combustion are discharged (Fig. 5). 

Fig. 5. — Fourth cycle: Exhaust. 

These various cycles succeed one another, passing 
through the same phases in the same order. 


Valve Mechanism.— It is to be noted that in mod- 
ern motors valves are used which arc better adapted to 
the peculiarities of explosion-engines than were the 
old slide-valves used when the Otto engine was first 
introduced. The slide-valve may now be considered 
as an antiquated distributing device with which it is 
impossible to obtain a low consumption. 

In old-time gas-engines rather low compressions were 
used. Consequently a very low explosive power of the 
gaseous mixture, and low temperatures were obtained. 
The slide-valves were held to their seats by the pres- 
sure of external springs, and were generously lubri- 
cated. Under these conditions they operated regularly. 
Nowadays, the necessity of using gas-engines which are 
really economical has led to the use of high compres- 
sions with the result that powerful explosions and high 
temperatures are obtained. Under these conditions 
slide-valves would work poorly. They would not be 
sufficiently tight. To lubricate them would be difficult 
and ineffective. Furthermore, large engines arc widely 
used in actual practice, and with these motors the fric- 
tional resistance of large slide-valves, moving on exten- 
sive surfaces would be considerable and would appre- 
ciably reduce the amount of useful work performed. 

By reason of its peculiar operation, the slide-valve 
is objectionable, the gases being throttled at the time of 
their admission and discharge. As a result of these ob- 
jections there are losses in the charge; and obnoxious 
counter-pressures occur. The necessity of using ele- 
ments simple in their operation and free from the ob- 


jections which have been mentioned, has naturally led 
to the adoption of the present valve. This valve is used 
both for the suction of the gas and of the air, as well as 
for the exhaust, with the result that either of these two 
essential phases in the operation of the motor can be 
independently controlled. The valves offer the follow- 
ing advantages : Their tightness increases with the pres- 
sure, since they always open toward the Interior of the 
cylinder (Fig. 6). They have no rubbing surfaces, 

Fig. 6.— Modern valve mechanism. 

and need not, therefore, be lubricated. Their opening 
is controlled by levers provided with quick-acting 
cams; and their closure is effected by coiled spring 
almost instantaneous in their action (Fig. y). Each- 
valve, depending upon the purpose for which it is used, 
can be mounted in that part of the cylinder best suited 
for its particular function. The types of valved motor! 
now used are many and various. In order to attain 



economy in consumption and regularity in operation 
they should meet certain essential requirements which 
will here be reviewed. 

Apart from proportioning the areas properly and 

from providing a suitable means of operation, it is in- 

1 dispensable that the valves should be readily accessible. 

Indeed, the valves should be regularly examined, 

Fie. 7. — ConlrollitiR mechanism of valve, 

cleaned and ground. It follows that it should be pos- 
sible to take them apart easily and quickly. ' 

It is necessary that the exhaust-valve be well cooled; 
otherwise the valve, exposed as it is to high tempera- 
tures, will suffer derangement and may cause leakage. 
The water-jacket should, therefore, surround the seat 
of the exhaust-valve, care being taken that the cooling 
water be admitted as near to it as possible (Fig. 8). 
The motor should control the air-let valve or that of 
the gaseous mixture. Hence these valves should not 


be actuated simply by springs, because springs ; 

to move under the influence of the vacuum produced 

by suction. 

The mixture of gas and air should not be admitted 
into the cylinder at too low a pressure; otherwise the 
weight of the mixture admitted would be lower than it 


ought to be, inasmuch as under these conditions the 
valve will be opened too tardily and closed prema- 
turely. At the beginning «as well as at the end of its 
stroke the linear velocity of the piston is quite inade- 
quate to create a vacuum sufficient to overcome the re- 
sistance of the spring. It is, therefore, generally the 
practice separately to control the opening or closing of 
the one or the other valve (gas-valve or mixture-valve) . 
Consequently these valves must be actuated independ- 
ently of each other. Nowadays they are mechanically 
controlled almost exclusively, — a method which is ad- 
vocated by well-known designers for industrial motors 
in particular. Valves which are not actuated in this 
manner (free valves) have only the advantage of sim- 
plicity of operation. Nevertheless, this arrangement 
is still to be found in certain oil and benzine engines, 
notably in automobile-motors. In these motors it is 
necessary to atomize the liquid fuel by means of aspired 
air, in order to produce an explosive, gaseous mixture. 

Ignition. — In the development of the gas-engine, the 
incandescent tube and the electric spark have taken the 
place of the obsolete naked flame. The last-mentioned 
mode of exploding the gaseous mixture will not, there- 
fore, be discussed. 

The hot tube of porcelain or of metal has the in- 
disputable merit of regularity of operation. The meth- 
ods by which this operation is made as perfect as 
possible are many. Since certainty of ignition is ob- 
tained by means of the tube, it is important to time the 
ignition, so that it shall occur exactly at the moment 

when the piston is at the dead center. It has been 
previously stated that premature or belated ignition of 
the explosive mixture appreciably lessens the amount 
of useful work performed by the expansion of the gas. 
If ignition occur too soon, the mixture will be exploded 
before the piston has reached the dead center on its 
return stroke. As a result, the piston must overcome a 
considerable resistance due to the premature explosion 
and the consequent pressure. Furthermore, by reason 
of the high temperature of explosion, the gaseous prod- 
ucts are very rapidly cooled. This rapid cooling causes 
a sudden drop in the pressure; and since a certain inter- 
val elapses between the moment of explosion and the 
moment when the piston starts on its forward stroke, 
the useful motive effort is the more diminished as the 
ignition is more premature. 

Incandescent Tubes. — In Figs. 9 and 10 two systems 
most commonly used are illustrated. In these two ar- 
rangements, in which no valve is used, the length or 
height to which the tube is heated by the outer flame is 
so controlled that the gaseous mixture, which has been 
driven into the tube after compression, reaches the 
incandescent zone as nearly as possible at the exact 
moment when ignition and explosion should take place. 
The temperature of the flame of the burner, the rich- 
ness of the gaseous mixture, and other circumstances, 
however, have a marked influence on the time of igni- 
tion, so that the mixture is never fired at the exact 
moment mentioned. 

These considerations lead to the conclusion that 



motors in which the mixture is exploded by hot tubes 
provided with an ignition-valve are preferable to valve- 
less tubes. By the use of a special valve, positively 
controlled by the motor itself, the chances of untimely 
ignition are lessened, because it is necessary simply to 
regulate the temperature and the position of the tube 
in order that ignition may be surely effected imme- 

— Valvelcss hot lubes. 

diately upon the opening of the valve, at the very mo- 
ment the cylinder gases come into contact with the in- 
candescent portion of the tube (Fig. it). Many manu- 
facturers, however, do not employ the ignition-valve on 
motors of less than 15 to 20 horse-power, chiefly because 
of the cheaper construction. The total consumption 


is of less moment in a motor of small than of great 
power, and the loss due to the lack of an ignition-valve 
not so marked. In a high-power engine, premature ex- 
plosion may be the cause of the breaking of a vital 
part, such as the piston-rod or the crank-shaft. For 
this reason, a valve is indispensable for engines of more 
than 2 oto 25 horse-power. A breakage of this kind is 
less to be feared in a small motor, where the parts are 

-tube with valve. 

comparatively stout. The gas consumption of a well- 
designed burner does not exceed from 3.5 to 5 cubic 
feet per hour. 

Electric Ignition — Electric ignition consists in pro- 
ducing a spark in the explosion-chamber of the engine. 
The nicety with which it can be controlled gives it an 
undeniable advantage over the hot tube. But the ob- 


3 1 

jection has been raised, perhaps with some force, that 
it entails certain complications in installing the engine. 
Its opponents even assert that the power and the rapid- 
ity of the deflagration of the explosive mixture are 
greater with hot-tube ignition. This reason may have 
caused the hot-tube system to prevail in England, 
where manufacturers of gas-engines are very numerous 
and not lacking in experience. 

Electric ignition is effected in gas-engines by means 
of a battery and spark-coil, or by means of a small mag- 
neto machine which mechanically produces a current- 
breaking spark. 

Electric Ignition by Battery and Induction-Coil.— 
The first system is the cheaper; but it exacts the most 

Fig. is, — Electric ignition by spark-coil and ballery. 

painstaking care in maintaining the parts in proper 
working condition. It comprises three essential ele- 
ments—a battery, a coil, and a spark-plug (Fig. 12). 
The battery may be a storage-battery, which must, con- 
sequently, be recharged from time to time; or it may be 

32 GAS- 


a primary battery which must be frequently renewed 
and carefully cleaned. The induction-coil is fitted with 
a trembler or interrupter, which easily gets out of order 
and which must be regulated with considerable accu- 
racy. The spark-plug is a particularly delicate part, 
subject to many possible accidents. The porcelain of 
which it is made is liable to crack. It is hard to obtain 

Fig. 13. — Spark-plug. 

absolutely perfect insulation; for the terminals deterio- 
rate as they become overheated, break, or become foul 
(Fig. 13). In oil-engines, especially, soot is rapidly 
deposited on the terminals, so that no spark can be pro- 
duced. In benzine or naphtha motors, such an accident 
is less likely to happen. In automobile-motors, how- 
ever, the spark-plug only too often fails to perform its 
function. The one remedy for these evils is to be found 



in the most painstaking care ot the spark-plug and of 
the other elements of the ignition system. 

Ignition by Magnetos. — Magneto apparatus, on the 
3ther hand, are noteworthy for the regularity of their 
Dperation. They may be used for several years with- 

Fio. 14. — Magneto ignition apparatus. 

>ut being remagnetized, and require no exceptional 
:are. Magneto ignition devices are mechanically ac- 
:uated, the necessary displacement of the coil being 
effected by means of a cam carried on a shaft turning 
tfith half the motor speed (Figs. 14 and 15). At the 
noment when it is released by the cam, the coil is sud- 


denly returned to its initial position by means of 
spring. This rapid movement generates a current that 
passes through terminals, which are arranged within 
the cylinder and which are immediately separated by 
mechanical means. Thus a much hotter circuit-break- 

& eCM 

magneto ignition apparatus. 

ing spark is produced, which is very much mon 
energetic than that of a battery and induction-coil, and 
which surely ignites the gaseous mixture in the cylii 
der. The terminals are generally of steel, sometime! 
pointed with nickel or platinum (Fig. 16). The t 
precaution to be observed is the exclusion of moistun 



and occasional cleaning. For engines driven by pro- 
ducer-gas magneto-igniters are preferable to cells and 

Fig. 16. — Contacts of a magneto-igniter. 

batteries. In general, electrical ignition is to be rec- 
ommended for high-pressure engines. 

In order to explain more clearly modern methods of 
ignition a diagram is presented, showing an electric 

Fig. 17. — Device for regulating the moment of ignition. 

magneto-igniter applied to the cylinder-head of a 
Winterthur motor, and also a sectional view of the 
member varying the make-and-break contacts which 


are mounted in the explosion-chamber (Figs. 18 and 

i 9 ). 

1. The magneto A consists of horseshoe-magnets, 
between the poles of which the armature rotates. At 
its conically turned end, the armature-shaft carries an 
arm B, held in place bv a nut. 

8, \\ hiiiriliur eleclric ignilion system. 

2. The igniter C is a casting secured to the cylinder- 
head by a movable strap and provided with two axes 
D and M, of which the one, D, made of bronze, is 
movable, and is fitted with a small interior contact- 
hammer, a percussion-lever, and an exterior recoil- 
spring; the other, M, is fixed, insulated, and arranged 



to receive the current from the magneto /t, by means 
of an insulated copper wire £. 

3. The spring F comprises two continuous coils con- 
tained in a brass casing, and actuating a steel striking 
or percussion-pin. 

4- The controlling devices of the magneto include a 
stem or rod G, slidable in a guide //, provided with a 

of thfl Winter! hur system. 

safety spring and mounted on an eccentric spindle, the 
position of which can be varied by means of a regulat- 
ing-lever (/). The rod is operated from the dis- 
tributing-shaft, on the conical end of which a cam / 
carrying a spindle is secured. 

Regulation of the Magneto. — The position assumed 
by the armature when at rest is a matter of importance 
in obtaining a good spark on breaking the circuit. The 
marks on the armature should be noted. The position 


of the armature may be experimentally varied, in order 
to obtain a spark of maximum intensity, by changing 
the position of the arm B on the armature-shaft, 

Control of the Magneto. — The controlling gear 
should enable the armature to oscillate from 20 to 25 
degrees. The time at which the breaking of the circuit 
. is effected can be regulated by shifting the handle {/). 
In starting the engine, the circuit can be broken with 
a slight retardation, which is lessened as the engine 
attains its normal speed. 

Igniter.— It is advisable that there should be a play 
of y 2 mm. (0.0196 in.) between the lever Z when at 
rest and the striking-pin. The axis D of the circuit- 
breaking device should be easily movable; and the 
hammer which it carries at its end toward the interior 
of the cylinder should be in perfect contact with the 
stationary spindle A/, which is electrically insulated. 
This spindle M should be well enclosed, in order to 
prevent any leakage that might cause a deterioration of 
the insulating material. 

The subject of ignition is of such extreme impor- 
tance that the author will recur to it from time to time 
in the various chapters of this book. Too much stress 
cannot be laid upon proper timing; otherwise there 
will be a needless waste of power. Cleanliness is a 
point that must be observed scrupulously; for spark- 
plugs are apt to foul only too readily, with the result 
that short-circuits and misfires are apt to occur. In 
oil and volatile hydrocarbon engines the tendency to 
fouling is particularly noticeable. In the chapter de- 



voted to these forms of motors the author has dwelt 
upon the precautions that should be taken to forestall a 
possible derangement of the ignition apparatus. As a 
general rule the ignition apparatus installed by trust- 
worthy manufacturers will be found best suited for the 
requirements of the engine. 

The apparatus should be fitted with a device by 
which the ignition can be duly timed by hand during 
operation (Fig. 17). 

The Piston. — Coming, as it does, continually in con- 
tact with the ignited gases, the piston is gradually 

Design of the piston. 

heated to a high temperature. The rear face of the 
piston should preferably be plane. Curved surfaces 
are not to be recommended because they cool off 
badly. Likewise, faces having either inserted parts 
or bolt-heads are to be avoided, since they are liable to 
become red-hot and to ignite the mixture prematurely 
{Fig. 20). 


Among the parts of the piston which rapidly wear 
away because constant lubrication is difficult, is the 
connection with the piston-rod (Fig. 21). It is im- 
portant that the bearing at the piston-pin be formed of 
two parts which can be adjusted to take up the wear. 
The pin itself should be of case-hardened steel. For 
large engines, some manufacturers have apparently 
abandoned the practice of locking the pin, by set-screws, 
in Ranges cast in one piece with the piston. Indeed, 
the piston is often fractured by reason of the expansion 
of the pins thus held on two sides. It seems advisable 

Fig. si. — Piston with lubricated pin. 

to secure the pin by means of a single screw in one of 
the flanges, fitting it by pressure against the opposite 
boss. The use of wedges or of clamping-screws, in- 
troduced from without the piston to hold the pin, 
should be avoided. It may happen that the wedges 
will be loosened, will move out, and will grind the 
cylinder, causing injuries that cannot be detected before 
it is too late. The strength of the piston-pin should be 
so calculated that the pressure per square inch of pro- 
jected surface does not exceed 1,500 to 2,850 pounds 
per square inch. It should be borne in mind that the 



initial pressure of the explosion is often equal to 400 to 
425 pounds per square inch. Some manufacturers 
mount the pin as far to the back of the piston as possi- 
ble, so as to bring it nearer the point of application of 
the motive force of the explosion. Other manufac- 
turers, on the other hand, mount the pin toward the 
front of the piston. No great objection can be raised 
against either method. In the former case the position 
of the rings will limit that of the pin. 

The number of these rings ought not to be less than 
four or five, arranged at the rear of the piston. It is 
to be observed that makers of good engines use as many 
as 8 to 10 rings in the pistons of fair-sized motors. 

Piston-rings of gray pig-iron can be adjusted with 
the greatest nicety in such a manner that, by means 
of tongues fitting in their grooves, they are held from 
turning in the latter, whereby their openings are pre- 
vented from registering and allowing the passage of 
gas. As a general rule, a large number of ring:; 
may be considered a distinguishing feature of a well- 
built engine. In order to prevent a too rapid wear of 
the cylinder, several German manufacturers finish off 
the front of the piston with bronze or anti-friction 
metal in engines of more than 40 to 50 horse-power. It 
is to be observed, however, that this expedient is not 
applicable to motors the cylinders -of which are com- 
paratively cold; otherwise the bronze or anti-friction 
metal will deteriorate. 

Arrangement of the Cylinder. — The cylinder shell 
or liner, in which the piston travels, and the water- 


jacket should preferably be made in separate pieces and 
not cast of the same metal, in order to permit a free 
expansion (Figs. 22 and 23). If for want of care or 

of proper lubrication, which frequently occurs in gas- 
engines, the cylinder should be injured by grinding, 
it can be easily renewed, without the loss of all the con- 
necting parts. 

For the same reason, the cylinder and its casing 

Fig. S3. — Cylinder with independent liner and head. 

should be independent of the frame. In many horizon- 
tal engines, the cylinders overhang the frame through- 
out the entire length, by reason of the joining of their 


front portions with the frames. Although such a con- 
struction is attended with no serious consequences in 
small engines, nevertheless in large engines it is ex- 
ceedingly harmful. Indeed, in most modern single- 
acting engines, the pistons are directly connected with 
the crank-shaft by the piston-rod, without any inter- 
mediate connecting-rod or cross-head. The vertical re- 

Fig. 24. — Single-acting engines. 

action of the motive effort on the piston is, therefore, 
taken up entirely by the thrust of the cylinder, which 
is also vertical (Fig. 24). This thrust, acting against 
an unsupported part, may cause fractures; at any rate, 
it entails a rapid deterioration of the cylinder joint. 

The Frame. — Gas-engines driven as they are, by ex- 
plosions, giving rise to shocks and blows, should be 
built with frames, heavy, substantial, and broad-based, 


so as to rest solidly on the ground. This essential con- 
dition is often fulfilled at the cost of the engine's ap- 
pearance; but appearance will be willingly sacrificed 
to meet one of the requirements of perfect operation. 
For engines of more than 8 to 10 horse-power, frames 
should be employed which can be secured to the 
masonry foundation without a separate pedestal or base. 
Some manufacturers, for the purpose of lightening the 
frame, attach but little importance to the foundation 

Fig. 15, — Engine witi] inclined bearings. 

and to strength of construction, and employ the design 
illustrated in place of the crank-shaft bearing (Fig. 
25) ; others, in order to facilitate the adjusting of the 
connecting-rod bearings, prefer the second form (Fig. 
26). It is evident that, in the first case, a part of the 
effort produced by the explosion reacts on the upper 
portion of the connecting-rod bearing, on the cap of 
the crank-shaft bearing, and consequently on the fas- 
tening-bolts. In the second case, if the adjustment 
be not very carefully made, or if the rubbing surfaces 
arc insufficient, the entire thrust due to the explosion 



will be received by the meeting parts of the two bush- 
ings, thus injuring them and causing a more rapid 
wear. In the construction of large engines, some manu- 

Fig. 26. — Engine with straight bearings. 

facturers take the precaution of forming the connect- 
ing-rod bearings of four parts, adjustable to take up the 
wear, so that the effort is exerted against the parts dis- 
posed at right angles to each other. A form that seems 
rational is that shown in Fig. 27, in which the reaction 

Fig. 27. — Engine with correctly designed bearings. 

of the thrust is taken up by the lower bearing, rigidly 
supported by the braced frame, in the direction oppo- 
site to that of the explosive effort. 


The sum of the projecting surfaces of the two bear- 
ings should be so calculated that a maximum explosive 
pressure of 405 to 425 pounds per square inch will not 
subject the bearings to a pressure higher than 425 to 
550 pounds per square inch. 

Fly- Wheels.— In gas-engines particularly, the fly- 
wheel should be secured to the crank-shaft with the ut- 
most care. It should be mounted as near as possible 
to the bearings; otherwise the alinement of the shaft 
will be destroyed and its strength impaired. If the fly- 
wheel be fastened by means of a key or wedge having- 
a projecting head, it is advisable to cover the end of the 
shaft by a movable sleeve. The fly-wheel should run 
absolutely true and straight even if the explosion be 
premature. In well-built engines the fly-wheels are 
lined up and shaped to the rim. The periphery is 
slightly rounded in order the better to guide the belt 
when applied to the wheel. 

Furthermore, fly-wheels should be nicely balanced; 
those are to be preferred which have no counter-weights 
cast or fastened to the hub, the spokes, or the rim. 

The system of balancing the engine by means of two 
fly-wheels, mounted on opposite sides, is used chiefly 
for the purpose of equalizing the inertia effects. Spe- 
cial engines, employed for driving dynamos, and even 
industrial engines of high power, are preferably fitted 
with but a single fly-wheel, with an outer bearing, since 
they more readily counteract the cyclic irregularities or 
variations of speed occurring in a single revolution 
(Fig. 28). If in this case a pulley be provided, 



should be mounted between the engine and the outer 
bearing. The following advantages may be cited 
favor of the single fly-wheel, particularly in the case of 
dynamo-driving engines: 

i. The single fly-wheel permits a more ready access 
to the parts to be examined. 

2. It involves the employment of a third bearing, 
thus avoiding the overhang caused by two ordinary fly- 

3. It avoids the torsional strain to which the two- 
wheel crank is subjected when starting, stopping, and 
changing the load, the peripheral resistance varying 
in one of the fly-wheels, while the other is subjected to 
a strain in the opposite direction on account of the 

4. Two fly-wheels, keyed as they are to projecting 
ends of the shaft, will be so affected at the rims by the 
explosions that the belts will shake. 

The third bearing which characterizes the single- 
fly-wheel system, is but an independent support, rest- 
ing solidly on the masonry bed of the engine. The 
bearing with its independent support is sufficiently 
rigid, and is not subjected to any stress from the crank 
at the moment of explosion, the reaction of the crank 
affecting only the frame bearings. With such fly- 
wheels, reputable firms guarantee a cyclic regularity 
which compares favorably with that of the best steam- 
engines. For a duty varying from a third of the load to 
the maximum load, these engines, when driving direct- 
current dynamos for directly supplying an electric- 



light circuit, will insure perfect steadiness of the light; 
and the effectually aperiodic measuring instruments 
will not indicate fluctuations greater than 2 to 3 per 
cent, of the tension or intensity of the current. The 
coefficient of the variations in the speed of a single rev- 
olution will thus be not far from ^. 
Straight and Curved Spoke Fly-Wheels.— The 

Fig. 29. — Curved spoke fly-wheel. 

spokes of fly-wheels are either straight or curved. In 
assembling the motor parts it too often occurs that 
curved spoke fly-wheels are mounted with utter dis- 
regard of the direction in which they are to turn. It 
is important that curved spokes should be subjected to 
compression and not to traction. Hence the fly-wheels 


should be so mounted that the concave portions of the 
spokes travel in the direction of rotation, as shown in 
the accompanying diagram (Fig. 29). If a single fly- 
wheel be employed on an engine of the type in which 


Fig. 30. — Forged crank -shafts. 

the speed is governed by the u hit-and-miss " system, 
the fly-wheel should be extra heavy to counteract the ir- 
regularities of the motive impulses when the engine is 
not working at its full load, or in other words, when no 
explosion takes place at every cycle. 

The Crank-Shaft. — The crank-shaft should be made 
of the best mild steel. Those shafts are to be preferred 




Fig. 31. — Correct design of crank -shaft. 

the cranks of which are riot forged on (Fig. 30), but 
cut out of the mass of metal; furthermore, the brackets 
or supports should be planed and shaped so that they 
are square in cross-section. 


5 1 

Such a design involves fine workmanship and speaks 
well for the construction of the whole engine. More- 
over, it enables the bearings to be brought nearer each 
other, reduces to a minimum that part of the crank- 
shaft which may be considered the weakest, and per- 
mits a rational and exact counterbalancing of the mov- 
ing parts, such as the crank and the end of the connect- 
ing-rod. The best manufacturers have adopted the 
method of fastening to the cranks balancing weights 
secured to the brackets, especially for high-speed cn- 

Fig. 32.— Crank-shaft with balancing weight. 

gines or for engines of high power. The projecting 
surface of the crank-pin should, as a rule, be calculated 
for a pressure of 1,400 pounds per square inch. 

Cams, Rollers, etc. — The cams, rollers, thrust-bear- 
ings, as well as the piston-pin in particular, should be 
made of good steel, case-hardened to a depth of at least 
.08 of an inch. Their hardness and the degree of 
cementation mav be tested bv means of a file. This is 
the method followed bv the best manufacturers. 

Bearings. — All the bearings zm\ all guides should 
be adjustable to take up the wear. They are usually 
made of bronze or of the best anti -friction metal. 

5 2 


Steadiness. —The steadiness of engines may be con- 
sidered from two different standpoints. 

i. Variation of the Number of Revolutions at Dif- 
ferent Loads. — This depends chiefly on the sensitive- 
ness of the governor, which should be of the " inertia " 
or of the " ball " (or centrifugal) type. The first form 
is rarely employed, except in small engines up to 10 
horse-power, and is applicable only to engines in which 

Fie. 33. —Inertia governor. 

the " hit and miss " system is employed ( Fig. 33 ) . The 
second form is more widely used, and is applicable to 
engines having "hit-and-miss" or variable admission 
devices. In the first form, the governor simplv displaces 
a very light member, whatever may be the size of the 
engine, for which reason the dimensions are very small. 
In the second form, on the other hand, the governor 
acts either on a conical sleeve or on some other regulat- 
ing member offering resistance. Evidently, in order t 



overcome the reactions to which it is subjected, it must 
be as heavy and powerful as a steam-engine governor. 
Sufficient allowance is made in a good engine for 
variation in the number of revolutions between no load 
and full load, not greater than two per cent, if the 
admission be of the " hit-and-miss " type, and five per 
cent, if it be of the variable type. 

2. Cyclic Regularity. — This term means simply that 
the speed of the engine is constant in a single revolu- 
tion. In practice this is never attained. Allowance is 
made in engines used for driving direct-current dyna- 
mos for a variation of about ^j while in industrial 
engines a variation of ^ is permissible. Cyclic varia- 
tion depends only on the weight of the fly-wheel; 
whereas variation in the number of revolutions is deter- 
mined chiefly by the governor. 

Governors. — Diagrams are here presented of the 
principal types of governors — the inertia governor, the 
ball or centrifugal governor controlling an admission- 
valve of the "hit-and-miss" type (Fig. 34), and the 
ball or centrifugal governor controlling a variable gas- 
admission valve (Fig. 35). 

In distinguishing between the operation of the two 
last-mentioned types, it may be stated that the former 
bears the same relation to the hit-and-miss gear as it 
does, for example, to the valve gear of a Corliss steam- 
engine. In other words, it is an apparatus that indi- 
cates without inducing, admission or cut-off. The sec- 
ond type, on the other hand, operates by means of slides 
and the like, as in the Ridder type of engine, in which 


it controls the displacement of the cut-off or distribu- 
tion slide-valve and is subjected to variable forces, de- 
pending on the pressure, lubrication, the condition of 
the stuffing-boxes, and the like. 

In gas as well as in steam engines, designs are to be 
commended which shield the delicate mechanism from 
strains and stresses that are likely to destroy its sensi- 

Fic. 34- — "Hit-and-miss" governor, 

tiveness, as is the case in the automatic cut-off of the 
Corliss steam-engine. 

Governors should be provided with means to permit 
the manual variation of the speed while the engine is in 

For small motors, one of the most widely used ad- 
mission devices is that of the " hit-and-miss " type. As 
its name indicates, this admission arrangement allows 


a given quantity of gas to enter the cylinder for a num- 
ber of consecutive intervals, until the engine is about 
to exceed its normal speed. Thereupon the governor 
cuts off the gas entirely. The result is that, in this 
system, the number of admissions is variable, but that 
each admitted charge is composed of a constant pro- 
portion of gas and air. 

The governors employed for the " hit-and-miss " 
type are either " inertia " or " centrifugal " governors. 

Inertia governors (Fig. 33) are less sensitive than 
those of the centrifugal type. They are generally ap- 
plied only to industrial engines of small power, in 
which regularity of operation is a secondary considera- 

Centrifugal governors employed for gas-engines 
with " hit-and-miss " regulation are, as a general rule, 
noteworthy for their small size, which is accounted for 
by the fact that, in most systems, merely a movable 
member is placed between the admission-controlling 
means and the valve-stem (Fig. 34). It follows that 
this method of operation relieves the governor of the 
necessity of overcoming the resistance of the weight of 
moving parts, more or less effectually lubricated, and 
subjected to the reaction of the parts which they con- 

In engines equipped with variable admission devices 
for the gas or the expl6sive mixture, the governor act- 
uates a sleeve on which the admission-cam is fastened 
(Fig. 35). Or, the governor may displace a conical 
cam, the reaction of which, on contact with the lever, 


destroys the stability of .the governor. These condi- 
tions justify the employment of powerful governors 
which, on account of the inertia of their parts, diminish 
the reactionary forces encountered. 

The centrifugal governor should be sufficiently ef- 
fectual to prevent variations in the number of revolu- 
tions within the limits of 2 to 3 per cent, between no 
load and approximately full load. Under equivalent 

Fig. 35. — Variable adi 

conditions, the inertia governor can hardly be relied 
upon for a coefficient of regularity greater than 4 to 
5 per cent. 

The manner of a governor's operation is necessarily 
dependent on the admission system adopted. And the 
admission system varies essentially with the size, the 
purpose of the engine, and the character of the fuel em- 

Vertical Engines. — For some years past there seems 
to have been a tendency in Europe to use horizontal 
instead of vertical engines, especially since engines of 



more than 10 or 15 horse-power have been extensively 
used for industrial purposes. The vertical type is used 
for 1 to 8 horse-power engines, with the cylinder in the 
lower part of the frame, and the shaft and its fly-wheel 
in the upper part (Fig. 36). The only merit to be 
attributed to this arrangement is a great saving of space. 
It is evident, however, that beyond a certain size and 
power, such engines are unstable. In America particu- 

Fig. 36. — Vertical engine. 

larly, many manufacturers of high-power engines (50 
to 100 horse-power or more) prefer the vertical or 
" steam-hammer " arrangement, which consists in plac- 
ing the cylinder in the upper part, and the shaft in the 
lower part of the frame as close to the ground as possi- 
ble (Figs. 37 and 38). The problem of saving space, as 
well as that of insuring stability, is thus solved, so that 
it is easily possible to run up the speed of the engine. 
There is also the advantage that the shaft of a dynamo 




can be directly coupled up with the crank-shaft of the 
engine, thus dispensing with a belt which, at the least. 





absorbs 4 to 6 per cent, of the total power. It should, 
nevertheless, be borne in mind that the direct coupling 


of electric generators to engine-shafts implies the use 
of extremely large and, therefore, of extremely costly 
dynamos. Furthermore, by reason of this arrangement, 
groups of elect ro-gene'ra tors can be disposed in a com- 
paratively small amount of space. Some English man- 
ufacturers are also beginning to adopt the "steam- 
hammer" type of engine for high powers, the result 
being a marked saving in material and lowering of the 
cost of installation. 

Power of the Engine.— The first thing to be con- 
sidered is that the power of a gas-engine is always given 
in " effective " horse-power, and that the power of a 
steam-engine is always given in " indicated " horse- 
power in contracts of sale. In England and in the 
United States, the expression " nominal " horse-power 
is still employed. It may be advisable to define these 
various terms exactly, since unscrupulous dealers, to 
the buyer's loss, have done much to confuse them. 

" Indicated " horse-power is a designation applied to 
the theoretical power produced by the action of the 
motive agent on the piston. The work performed is 
measured on an indicator card, by means of which the 
average pressure to be considered in the computation of 
the theoretical power is ascertained. 

The " effective " or brake horse-power is equal to the 
" indicated " horse-power, less the energy absorbed by 
passive resistance, friction of the moving parts, etc. 

The "effective" work is an experimental term ap- 
plied to the power actually developed at the shaft. 
This work is of interest solely to the engine user. 



In a well-built motor, in which the passive resistance 
by reason of the correct adjustment and simplicity of 
the parts, is reduced to a minimum, the " effective " 
horse-power is about 80 to 87 per cent, of the " indi- 
cated " horse-power, when the engine runs under full 
load. This reduced output is usually called the 
"mechanical efficiency'" of the engine. 

" Nominal " horse-power is an arbitrary term in the 
sense in which it is used in England and America, 
where it is quite common. The manufacturers tbetn- 
selves do not seem to agree on its absolute value. A 
" nominal " horse-power, however, is equal to anything 
from 3 to 4 " effective " horse-power. The uncertainty 
which ensues from the use of the term should lead to 
its abandonment. 

In installing a motor, the determination of its horse- 
power is a matter of grave importance, which should 
not be considered as if the motor were a steam-engine 
or an engine of some other type. It must not be for- 
gotten that, especially at full load, explosion-engines 
are most efficient, and that, under these conditions, it 
will generally be advisable to subordinate the utility of 
having a reserve power to the economy which follows 
from the employment of a motor running at a load 
close to its maximum capacity. On the other hand, the 
gas-engine user is unwilling to believe that the stipu- 
lated horse-power of the motor which is sold to him is 
the greatest that it is capable of developing under in- 
dustrial conditions. Business competition has led some 
firms to sell their engines to meet these conditions. It 


is probably not stretching the truth too far to declare 
that 80 per cent, of the engines sold with no exact con- 
tract specifications are incapable of maintaining for 
more than a half hour the power which is attributed 
to them, and which the buyer expects. It follows that 
the power at which the engine is sold should be both 
industrially realized and maintained, if need be, for an 
entire dav, without the engine's showing the slightest 
perturbation, or faltering in its silent and regular opera- 
tion. To attain this end, it is essential that the energy 
developed by the engine in normal or constant opera- 
tion should not exceed 90 to 95 per cent, of the maxi- 
mum power which it is able to yield, and which may be 
termed its " utmost power." As a general rule, 
especially for installations in which the power fluctu- 
ates from the lowest possible to double this, as much 
attention must be paid to the consumption at half load 
as at full load; and preference should be given to the 
engine which, other things being equal, will operate 
most economically at its lowest load. In this case the 
consumption per effective horse-power is appreciably 
higher. Generally, this consumption is greater by 20 
to 30 per cent, than that at full load. This is partic- 
ularly true of the single-acting engines so widely used 
for horse-powers less than too to 150. 

In some double or triple-acting engines, according 
to certain writers, the diminution in the consumption 
will hardly be proportional to the diminution of the 
power, or at anv rate, the difference between the con- 
sumption per B. H. P. at full load and at reduced load 



will be less than in other engines. It should be ob- 
served, however, that this statement is apparently not 
borne out by experiments which the author has had 
occasion to make. To a slight degree, this economy is 
obtained at the cost of simplicity, and consequently, at 
the cost of the engine. At all events, the engines have 
the merit of great cyclic regularity, rendering them 
serviceable for driving electric-light dynamos; but this 
regularity can also be attained by the use of the extra 
heavy fly-wheels which English firms, in particular, 
have introduced. 

Automatic Starting. — When the gas-engine was first 
introduced, starting was effected simply by manually 
turning the fly-wheel until steady running was assured. 
This procedure, altogether too crude in its way, is 
attended with some danger. In a few countries it is 
prohibited by laws regulating the employment of in- 
dustrial machinery. If the engine be of rather large 
size — one, moreover, which operates at high pres- 
sure — such a method of starting is very troublesome. 
For these reasons, among others, manufacturers have 
devised automatic means of setting a gas-engine in 

Of such automatic devices, the first that shall be 
mentioned is a combination of pipes, provided with 
cocks, by the manipulation of which, a certain amount 
of gas, drawn from the supply pipe, is introduced into 
the engine-cylinder. The piston is first placed in a 
suitable position, and behind it a mixture is formed 
which is ignited by a naked flame situated near a con- 

oi resist 


venient orifice. When the explosion takes place the 
ignition-orifice is automatically closed, and the piston 
is given its motive impulse. The engine thus started 
continues to run in accordance with the regular recur- 
rence of the cycles. In this system, starting is effected 
by the explosion of a mixture, without previous com- 

Some designers have devised a system of hand- 
pumps which compress in the cylinder a mixture of 
air and gas, ignited at the proper time by allowing it 
to come into contact with the igniter, through the man- 
ipulation of cocks (Fig. 39). 

These two methods are not absolutely effective. 
They require a certain deftness which can be acquired 
only after some practice. Furthermore, they are ob- 
jectionable because the starting is effected too violently, 
and because the instantaneous explosion subjects the 
stationary piston, crank, and fly-wheel to a shock so 
sudden that they may be severely strained and may even 
break. Moreover, the slightest leakage in one of the 
valves or checks may cause the entire system to fail, 
and, particularly in the case of the pump, may induce 
a back explosion exceedingly dangerous to the man in 
charge of the engine. 

These systems are now almost generally supplanted 
by the compressed-air system, which is simpler, less 
dangerous, and more certain in its effect. 

The elements comprising the system in question in- 
clude essentially a reservoir of thick sheet iron, capable 
of resisting a pressure of 180 to 225 pounds and suffi- 

the reservoir is charged by the engine itself operatively 
connected with the compressor, or by an independent 
compressor, mechanically operated. 

In the first case, the pipe is provided with a stop- 
cock, mounted adjacent to the cylinder, and with a 
check-valve. When the engine is started and the gas 


cut off, the air is drawn in at each cycle and driven 
back into the reservoir during the period of compres- 
sion. When the engine, running under these conditions 
by reason of the inertia of the fly-wheel, begins to slow 
down, the check-valve is closed and the gas-admission 
valve opened, so as to produce several explosions and to 
impart a certain speed to the engine in order to con- 
tinue the charging of the reservoir with compressed air. 
This done, the valve on the reservoir itself is tightlv 
closed, as well as the check-valve, so as to avoid any 
leakage likely to cause a fall in the reservoir's pressure. 
In the second case, which applies particularly to 
engines of more than 50 horse-power, the charging pipe 
connected with the reservoir is necessarily independent 
of the pipe by means of which the motor is started. 
The reservoir having been filled and the decompres- 
sion cam thrown into gear, starting is accomplished : 

1. By placing the piston in starting position, which 
corresponds with a crank inclination of 10 to 20 degrees 
in the direction of the piston's movement, from the 
rear dead center, immediately after the period of com- 

2. Bv opening the reservoir-valve; 

3. By allowing the compressed air to enter the 
cylinder rapidly, through the quick manipulation of 
the stop-cock, which is closed again when the impulse 
is given and reopened at the corresponding period of 
the following cycle, this operation being repeated sev- 
eral times in order to impart sufficient speed to the 


4. By opening the gas-valve and finally closing the 
two valves of the compressed-air pipe. 

The pipes and compressed-air reservoirs should be 
perfectly tight. The reservoirs should have a capacity 
in inverse ratio to the pressure under which they are 
placed, i.e., they increase in size as the pressure de- 
creases. If, for example, the reservoirs should be op- 
erated normally at a pressure of 105 to 120 pounds per 
square inch, their capacity should be at least five or six 
times the volume of the engine-cylinder. If these res- 
ervoirs are charged by the engine itself, the pressure 
will always be less by 15 to 20 per cent, than that 
of the compression. 



In the preceding chapter the various structural de- 
tails of an engine have been summarized and those ar- 
rangements indicated which, from a general stand- 
point, seem most commendable. No particular system 
has been described in order that this manual might be 
kept within proper limits. Moreover, the best-known 
writers, such as Hutton, Hiscox, Parsell and Weed, in 
America; Aime Witz, in France; Dugald Clerk, Fred- 
erick Graver, and the late Bryan Donkin, in England; 
Guldner, Schottler, Thering, in Germany, have pub- 
lished very full descriptive works on the various types 
of engines. 

We shall now consider the various methods which 
seem preferable in installing an engine. The directions 
to be given, the author believes, have not been hitherto 
published in any work, and are here formulated, after 
an experience of fifteen years, acquired in testing over 
400 engines of all kinds, and in studying the methods 
of the leading gas-engine-building firms in the chief 
industrial centers of Europe and America. 

Location.- — The engine should be preferably located 
in a well-lighted place, accessible for inspection and 
maintenance, and should be kept entirely free from 



dust. As a general rule, the engine space should be en- 
closed. An engine should not be located in a cellar, on 
a damp floor, or in badly illuminated and ventilated 

Gas-Pipes. — The pipes by which fuel is conducted 
to engines, driven by street-gas, and the gas-bags, etc., 
are rarely altogether free from leakage. For this 
reason, the engine-room should be as well ventilated as 
possible in the interest of safety. Long lines of pipe 
between the meter and the engine should be avoided, 
for the sake of economy, since the chances for leakage 
increase with the length of the pipe. It seldom happens 
that the leakage of a pipe 30 to 50 feet long, supplying 
a 30 horse-power engine, is much less than 90 cubic feet 
per hour. The beneficial effect of short supply pipes 
between meter and engine on the running of the engine 
is another point to be kept in mind. 

An engine should be supplied with gas as cool as 
possible, which condition is seldom realized if long 
pipe lines be employed, extending through workshops, 
the temperature of which is usually higher than that of 
underground piping. On the other hand, pipes should 
not be exposed to the freezing temperature of winter, 
since the frost formed within the pipe, and particularly 
the crystalline deposition of naphthaline, reduces the 
cross section and sometimes clogs the passage. Often 
it happens that water condenses in the pipes; conse- 
quently, the piping should be disposed so as to obviate 
inclines, in which the water can collect in pockets. An 
accumulation of water is usually manifested by fluctua- 



tions in the flame of the burner. In places where water 
can collect, a drain-cock should be inserted. In places 
exposed to frost, a cock or a plug should be provided, 
so that a liquid can be introduced to dissolve the naph- 
thaline. To insure the perfect operation of the engine, 
as well as to avoid fluctuations in nearby lights, pipes 
having a large diameter should preferably be em- 
ployed.- The cross-section should not be less than that 
of the discharge-pipe of the meter, selected in accord- 
ance with the prescriptions of the following table: 


— * 


head} How. 


<*0 in h 


of pip* 

P.— of .„- 





3 burnm 

1 4. 





■/, h.-p. 

S " 

24-71° " 





!/. " 

IO ' 

49.420 " 



11 tV 


1-2 " 

20 " 

98.840 " 





3-4 " 

3° " 

148.160 " 



'8 A 


5-6 " 


247.100 " 





7-10 ■ 

60 " 

296.520 " 





11-14 " 

80 " 

395-36o " 





'5"'9 " 

IOO " 

494.200 ' 


33 A 




'5° " 

741.300 ' 

4° A 


33 \ I 



The records made are exact only when the meters 
( Fig. +0) are installed and operated under normal con- 
ditions. Two chief causes tend to falsify the measure- 
ments in wet meters: (i) evaporation of the water, (2) 
the failure to have the meter level. 

Evaporation occurs incessantly, owing to the flow- 
ing of the gas through the apparatus, and increases with 
a rise in the temperature of the atmosphere surrounding 
the meter. Consequently this temperature must be kept 


7 1 

down, for which reason the meter should be placed as 
near the ground as possible. The evaporation also in- 
creases with the volume of gas delivered. Hence the 
meter should not supply more than the volume for 
whith it was intended. In order to facilitate the re- 
turn of the water of condensation to the meter and to 
prevent its accumulation, the pipes should be inclined 
as far as possible toward the meter. The lowering of 

Fig. 40.— Wet gas- 

the water-level in the meter benefits the consumer at 
the expense of the gas company. 

Inclination from the horizontal has an effect that 
varies with the direction of inclination. If the meter 
be inclined forward, or from left to right, the water 
can flow out by the lateral opening at the level, and in- 
correct measurements are made to the consumer's cost. 

During winter, the meter should be protected from 
cold. The simplest way to accomplish this, is to wrap 
substances around the meter which are poor conductors 
of heat, such as straw, hay, rags, cotton, and the like. 
Freezing of the water can also be prevented by the addi- 

7 2 


tion of alcohol in the proportion of 2 pints per burner. 
The water is thus enabled to withstand a temperature 
of about 5 degrees F. below zero. Instead of alcohol, 
glycerine in the same proportions can be employed, 
care being taken that the glycerine is neutral, in order 

Fie. 4 

that the meter may not be attacked by the acids which 
the liquid sometimes contains. 

Dry Meters. — Dry meters are employed chiefly in 
cold climates, where wet meters could be protected only 
with difficulty and where the water is likely to freeze. 
In the United States the dry meter is the type most 
widely employed. In Sweden and in Holland it is also 
generally introduced (Fig. 41). 

In the matter of accuracy of measurement there is 
little, if any, difference between wet and dry meters. 
The dry meter has the merit of measuring correctly re- 



gardless of the fluctuations in the water level. On the 
other hand, it is open to the objection of absorbing 
somewhat more pressure than the wet meter, after hav- 
ing been in operation for a certain length of time. 

This is an objection of no great weight; for there is 
always enough pressure in the mains and pipes to 
operate a meter. 

In many cases, where the employment of non-freez- 
ing liquids is necessary, the dry meter may be used to 



advantage, since all such liquids have more or less cor- 
roding effect on sheet lead and even tin, depending 
upon the composition of the gas. 

The dry meter comprises two bellows, operating in 
a casing divided into two compartments by a central 

Fig. J3- - Section ihmugh a dry gas-mcler. 

partition. The gas is distributed on one or the other 
side of the bellows, by slides B. The slides 13 are pro- 
vided with cranks E, controlled by levers M, act- 
uated by transmission shafts O, driven by the bellows. 
The meter is adjusted by a screw which changes the 
throw of the cranks £ and consequently affects the be'l- 



lows. The movement of the crank-shaft D is trans- 
mitted to the indicating apparatus. In order to obvi- 
ate any leakage, this shaft passes through a stuffing-box, 

Fig. 44. — Rubber bag lo prevent fluctuations of the ignition flame. 

G. The diagrams (Figs. 42-43) show the construction 
of a dry meter, the arrows indicating the course taken 
by the gas. 

Care should be taken to provide the gas-pipe with 
a drain-cock, at a point near the engine. By means of 
this cock, any air in the pipe can be allowed to 


Fig. 45.— Rubber bags on gas-pipes. 



escape before starting; otherwise the engine can be set 
in motion only with difficulty. If the engine be pro- 
vided with an incandescent tube, the gas-supply pipe of 
the igniter should be fitted with a small rubber pouch 
or bag, in order to obviate fluctuations in the burner 
flame, caused by variations in the pressure (Fig. 44). 
As a general rule, the supplv-pipe should be connected 
with the main pipe on the forward side of the bags and 
gas-governors. The main pipe and all other piping 
near the engine should extend underground, so that 
free access to the motor from all sides can be obtained, 
without possibility of injury. 

Anti-pulsators, Bags, Pressure-Regulators. —The 
most commonly employed means of preventing fluctua- 
tion of nearby lights, due to the sharp strokes of the en- 
gine, consists in providing the gas-supply pipe with rub- 
ber bags (Fig. 45), which form reservoirs for the gas 
and, by reason of their elasticity, counteract the effect 
produced by the suction of the engine. Nevertheless, in 
order to insure a supply of gas at a constant pressure, 
which is necessary for the perfect operation of the en- 
gine, there are generally used, in addition to the bags, 
devices called gas-governors, or anti-pulsators (Fig. 


Although these devices are constructed in different 
ways, the underlying principle is the same in all. They 
comprise a metallic casing, containing a flexible dia- 
phragm of rubber or of some fabric impermeable to 
gas. Suction of the engine creates a vacuum in the cas- 
ing. The diaphragm bends, thereby actuating a valve, 


which cuts off the gas supply. During the three fol- 
lowing periods (compression, explosion, and exhaust) 
the gas, by reason of its pressure on the diaphragm, 
opens the valve and fills the casing, ready for the next 
suction stroke. 

Other devices, which are never sold with the engine, 
but are rendered necessary by reason of the condkions 
imposed by the gas supply are sold under the name 

Fro, 46— -^n 


"pressure-regulators" (Fig. 47). They consist of a 
bell, floating in a reservoir containing water and gly- 
cerine (or mercury), and likewise actuate a valve 
which partially controls the flow of gas. This valve 
being balanced, its mechanical action is the more cer- 
tain. Such devices are very effective in maintaining 
the steadiness of lights. On the other hand, they are 
often an obstacle to the operation of the engine be- 
cause thev reduce the flow and pressure of the gas too 
much. In order to obviate this difficulty, a pressure- 
regulator should be chosen with discrimination, and of 




sufficiently large size to insure the maintenance of an 
adequate supply of gas to the engine. Frequent ex- 
aminations should be made to ascertain if the bell of 
the regulator is immersed in the liquid. In the case of 
anti-pulsators, care should be taken that they are not 
spattered with oil. which has a disastrous effect on rub- 
ber. Anti-pulsators are generally mounted about 4 


Fig. 47. — A pressure -regulator. 

inches from a wall, in order that the diaphragm may 
be actuated by hand, if need be, 

Precautions. — In order not to strain the rubber of 
the bags or of the anti-pulsators, it is advisable to place 
a stop-cock in advance of these devices so that they can 
not be filled while the motor is at rest. 

The capacity of the rubber bags that can be bought 


in the market being limited, it is necessary to place one, 
two, or three extra bags in series (Figs. 48 and 49), for 
large pipes; but it should be borne in mind that the 

Figs. 48-49. — Arrangement of rubber bags. 

total section of the branch pipes should be at least equal 
to that of the main pipe. It is also advisable to extend 
the tube completely through the bag as shown in Figs. 
48 and 49. 

If there be two branch pipes the minimum diameter 



which meets this requirement is ascertained as follows: 
Draw to any scale a semicircle having a diameter 
equal or proportional to that of the main pipe (Fig. 
50). The sides of the isosceles triangle inscribed with- 
in this semicircle give the minimum diameter of each 
of the branch pipes. 

Sometimes engines are provided with a cock having 
an arrangement by means of which the gas feed is per- 
manently regulated, according to the quality and pres- 

Fig. 50. Fig. 51, 

sure of the gas and according to the load at which the 
engine is to run. This renders it possible to open the 
cock always to the same point ( Fig. 51). 

Air Suction. — In a special chapter the precautions to 
be taken to counteract the influence of the suction of the 
engine in causing vibration will be treated. The man- 
ner in which the suction of air is effected necessarily 
has as marked an influence on the operation of the en- 
gine as the supply of gas, since air and gas constitute 
the explosive mixture. 

Resistance to the suction of air should be carefully 

avoided, for which reason the length of the pipe should 
be reduced to a minimum, and its cross-section kept at 
least equal to that of the air inlet of the engine. Since 
the quality of street-gas varies with each city, the 
proper proportions of gas and air are not constant. In 
order that these proportions may be regulated, it is a 
matter of some importance to (it some suitable device 
on the pipe. Good engines are provided with a plug 
or flap valve. Generally the air-pipe terminates either 
in the hollowed portion of the frame, or in an inde- 
pendent pot, or air chest. The first arrangement is not 
to be recommended for engines over 20 to 25 horse- 
power. Accidents may result, such as the breaking of 
the frame by reason of back firing, of which more will 
be said later. If an independent chest be employed, its 
closeness to the ground renders it possible for dust 
easily to pass through the air-holes in the walls at the 
moment of suction, and even to enter the cylinder, 
where its presence is particularly harmful, leading, as 
it does, to the rapid wear of the rubbing surfaces, 
evil can be largely remedied by filling the air-chest 
with cocoa fiber or even wood fiber, provided the latter 
does not become packed down so as to prevent the air 
from passing freely. Such fibers act as air-filters. Reg- 
ular cleaning or renewal of the fiber protects the cylin- 
der from wear. In a general way, care should be 
taken, before fitting both the gas and air pipes, to tap 
the pipes, elbows, and joints lightly with a hammer on 
the outside in order to loosen whatever rust or sand 
may cling to the interior; otherwise this foreign m 


may enter the cylinder and cause perturbations in the 
operation of the engine. Under all circumstances, care 
should be taken not to place the end of the air-pipe 
under the floor or in an enclosed space, because leakage 
may occur, due to the bad seating of the air-valve, there- 
by producing a mixture which may explode if the 
flame leaps back, as we shall see in the discussion of 
suction by pipes terminating in the hollow of the frame. 
On the other hand, sand or saw-dust should not be 
sprinkled on the floor. 

Exhaust. — For the exhaust, cast-iron or drawn pipes 
as short as possible should be used. Not only the power 
of the engine, but also its economic consumption, can be 
markedly affected by the employment of long and bent 
pipes. Resistance to the exhaust of the products of 
combustion not only causes an injurious counter-pres- 
sure, but also prevents the clearing of the cylinder of 
burnt gases, which contaminate the aspired mixture 
and rob it of much of its explosiveness. The necessity 
of evacuating the cylinder as completely as possible is, 
nevertheless, not always reconcilable with local sur- 
roundings. To a certain extent, the objections to long 
exhaust-pipes are overcome by rigorously avoiding the 
use of elbows. Gradual curves are preferable. In the 
case of very long pipes it is advisable to increase their 
diameter every 16 feet from the exhaust. The exhaust- 
chest should be placed as near as possible to the engine; 
it should never be buried ; for the joints of the inlet and 
outlet pipes of the exhaust-chest should be easily acces- 
sible, so that they may be renewed when necessary. The 


author recommends the placing of the exhaust-chest in 
a masonry pit, which can be closed with a sheet-metal 
cover. For engines of 20 horse-power and upward, 
these joints should be entirely of asbestos. Pipes 
screwed directly into the casting are liable to rust. Ex- 

Fig. 52. — Method of mourning ptpw, 

posed as they are to the steam or water of the exhaust, 
they cannot be detached. 

The water, which results from the combination of 
the hydrogen of the gas with the oxygen of the air, is 
deposited in most cases at the bottom of the exhaust- 
chest. It is advisable to fit a plug or iron cock in the 
base of the chest. Alkaline or acid water will always 
corrode a bronze cock. In order that the pipes may 
not also be attacked, they are not disposed horizontally, 


but are given a slight incline toward the point where 
the water is drained off. If pipes of some length be 
employed, they should be able to expand freely with- 
out straining the joints, as shown in the accompany- 
ing diagram (Fig. 52), in which the exhaust-chest 
rests on iron rollers which permit a slight displace- 

For the sake of safety, at least that portion of the 
piping which is near the engine should be located at a 
proper distance from woodwork and other combustible 
material. By no means should the exhaust discharge 
into a sewer or chimney, even though the sewer or 
chimney be not in use; for the unburnt gases may be 
trapped, and dangerous explosions may ensue at the 
moment of discharge. 

The joints or threaded sleeves employed in assem- 
bling the exhaust-pipe should be tested for tightness. 
The combined action of the moisture and heat causes 
the metal to rust and to deteriorate very rapidly at 
leaky spots. 

When several engines are installed near one another, 
each should be provided with a special exhaust-pipe; 
otherwise it may happen, when the engines are all 
running at once, that the products of combustion dis- 
charged by the one may cause a back pressure detri- 
mental to the exhaust of the next. 

It is possible to employ a pipe common to all the ex- 
hausts if the pipe starts from a point beyond the ex- 
haust-chests, in which case Y-joints and not T-joints 
are to be used. 



The manner of securing the pipes to walls by mea 
of detachable hangers, lined with asbestos, is shown in 
a general way in the accompanying Fig. 53. The 
object of this arrangement is to render detachment 
easy and to prevent the transmission of shocks to the 

The precautions to be taken for muffling the noise of 
the exhaust will be discussed later. 

The end of the exhaust-pipe should be slightly 

Fig. 53.— Method of securing pipes lo walls. 
curved down in order to prevent the entrance of rain. 
Exhaust-pipes are subjected to considerable vibration, 
due to the sudden discharge of the gases. To protect 
the joints, the pipes should be rigidly fastened in place. 
Legal Authorization. — In most countries gas-en- 
gines may be installed only in accordance with the 
provision of general or local laws, which impose cer- 
tain conditions. These laws vary with different local- 
ities, for which reason they are not discussed here. 



THE reader will remember from what has already 
been said that a gas-engine is a motor which, more than 
any other, is subjected to forces, suddenly and re- 
peatedly exerted, producing violent reactions on the 
foundation. It follows that the foundation must be 
made particularly resistant by properly determining its 
shape and size and by carefully selecting the material 
of which it is to be built. 

The Foundation Materials. — Well-hardened brick 
should be used. The top course of bricks should be 
laid on edge. It is advisable to increase the stability 
of the foundation by longitudinally elongating it to- 
ward the base, as shown in the accompanying diagram 

(Fig. 54). 
As a binding material, only mortar composed of 

coarse sand or river sand and of good cement, should 
be used. Instead of coarse sand, crushed slag, well- 
screened, may be employed. The mortar should con- 
sist of 2 /i slag and ^ cement. Oil should not in any 
way come into contact with the mortar; it may perco- 
late through the cement and alter its resistant qualities. 
As in the construction of all foundations, care should 

be taken to excavate down to good soil and to line the 



bottom with concrete, in order to form a single mass of 
artificial stone. A day or two should be allowed for 
the masonry to dry out, before filling in around it, 

When the engine is installed on the ground floor 
above a vaulted cellar, the foundation should not rest 

directly on the vault below or on the joists, but should 
be built upon the very floor of the cellar, so that it 
passes through the planking of the ground floor with- 
out contact. 

When the engine is to be installed on a staging, the 



method of securing it in place illustrated in Fig. 55 
should be adopted. 

Although a foundation, built in the manner de- 
scribed, will fulfill the usual conditions of an industrial 
installation, it will be inadequate for special cases in . 
which trepidation is to be expected. Such is the case 
when engines are to be installed in places where, ow- 
ing to the absence of factories, it is necessary to avoid 

Fig. 55. — Elevated foundation. 

all nuisance, such as noise, trepidations, odors, and 
the like. 

Vibration. — In order to prevent the transmission of 
vibration, the foundation should be carefully insulated 
from all neighboring walls. For this purpose various 
insulating substances called " anti-vibratory " are to be 
recommended. Among these may be mentioned horse- 
hair, felt packing, cork, and the like. The efficacy 
of these substances depends much on the manner in 
which they are applied. It is always advisable to inter- 
pose a layer of one of these substances, from one to four 
inches thick, between the foundation and the surround- 
ing soil, the thickness varying with the nature of the 


material used and the effect to be obtained. Between 
the bed of concrete, mentioned previously, and the 
foundation-masonry and between the foundation and 
the engine-frame, a layer of insulating material may 
well be placed. Preference is to be given to substances 
not likely to rot or at least not likely to lose their in- 
sulating property, when acted upon by heat, moisture 
or pressure. 

Here it may not be amiss to warn against the utiliza- 
tion of cork for the bottom of the foundation; for water 
may cause the cork to swell and to dislocate the founda- 
tion or destroy its level. 

The employment of the various substances men- 
tioned does not entail anv great expense when the 
foundations are not large and the engines are light. 
But the cost becomes considerable when insulating ma- 
terial is to be employed for the foundation of a 30 to 50 
horse-power engine and upwards. For an engine of 
such size the author recommends an arrangement as 
simple as it is efficient, which consists in placing the 
foundation of the engine in a veritable masonry basin, 
the bottom of which is a bed of concrete of suitable 
thickness. The foundation is so placed that the lateral 
surfaces are absolutely independent of the supporting- 
walls of the basin thus formed. Care should be taken 
to cover the bottom with a laver of dry sand, rammed 
down well, varying in thickness with each case. This 
layer of sand constitutes the anti-vibratory material and 
confines the trepidations of the engine to the founda- 



As a result of (his arrangement, it should be ob- 
served that, being unsupported laterally, the founda- 
tion should be all the more resistant, for which reason 
the base-area and weight should be increased by 30 to 
40 per cent. The expense entailed will be largely off- 
set by saving the cost of special anti-vibratory sub- 
stances. In places liable to be flooded bv water, the 
basin should be cemented or asphalted. 

When the engine is of some size and is intended for 
the driving of one or more dynamos which may (hem- 
selves give rise to vibrations, the dynamos are secured 
directly to the foundation of the engine, which is ex- 
tended for that purpose, so that both machines are car- 
ried solidly on a single base. 

The foregoing outline should not lead the proprie- 
tor of a plant to dispense with the services of expertl, 
whose long experience has brought home to them the 
difficulties to be overcome in special cases. 

It should here be stated, as a general rule, that the 
bricks should be thoroughly moistened before they arc 
laid in order that they may grip the mortar. 

After having been placed on the foundation am! 
roughly trimmed with respect to the transmission de- 
vices, the engine is carefully leveled by means of hard- 
wood wedges driven under the base. This done, the 
bolts are sealed bv very gradually pouTing a cement 
wash into the holes, and allowing it to set. When the 
holes are completely filled and the bolts securely fas- 
tened in place, a shallow rim, or edge of clay, or sand 
is run around the cast base, so as to form a small box 



or trough, in which cement is also poured for the pur- 
pose of firmly binding the engine frame and founda- 
tion together. When, as in the case of electric-light 
engines, single extra-heavy fly-wheels are employed, 
provided with bearings held in independent cast sup- 
ports, the following rule should be observed to prevent 
the overheating due to unlevelness, which usually oc- 
curs at the bushings of these bearings: That part of the 
foundation which is to receive such a support should 
rest directly on the concrete bed and should be rigidly 
connected at the bottom with the main foundation. 
When the foundation is completely blocked up, the fly- 
wheel bearing with its support is hung to the crank- 
shaft; and not until this is effected is the masonry at 
the base of the support completed and rigidly fixed in 
its proper position. 

For very large engines, the foundation-bolts should 
be particularly well sealed into the foundation. In 
order to attain this end the bricks are laid around the 
bolt-holes, alternately projected and retracted as shown 
in Fig. 54. Broken stone is then rammed down around 
the fixed bolt; in the interstices cement wash is poured. 

Air Vibration, etc. — Vibration due chiefly to the 
transmission of noises and the displacement of air by 
the piston should not be confused with the trepidations 
previously mentioned. 

The noise of an engine is caused by two dis- 
tinct phenomena. The one is due to the transmit- 
ting properties of the entire solid mass constituting 
the frame, the foundation, and the soil. The other is 



due to vibrations transmitted to the air. In both cases, 
in order to reduce the noise to a minimum, the moving 
parts should be kept nicely adjusted, and above all, 
shocks avoided, the more harmful of which are caused 
by the play between the joint at the foot of the connect- 
ing-rod and the piston-pin, and between the head of the 
connecting-rod and the crank-shaft. 

Although smooth running of the engine may be as- 
sured, there is always an inherent drawback in the 
rapid reciprocating movement of the piston. In large, 
single-acting gas-engines, a considerable displacement 
of air is thus produced. In the case of a forty horse- 
power engine having a cylinder diameter and piston- 
stroke respectively of 13^4 inches and 213/5 inches, it ' 
is evident that at each stroke the piston will displace 
about 2 cubic feet of air, the effect of which will be 
doubled when it is considered that on the forward 
stroke back pressure is created and on the return stroke 
suction is produced. 

The air motion caused by the engine is the more 
readily felt as the engine-room is smaller. If the room, 
for example, be 9 feet by 75 feet by 8 feet, the volume 
will be 1,080 cubic feet. From this it follows that the 
2 cubic feet of air in the case supposed will be alter- 
nately displaced six times each second, which means 
the displacement of 12 cubic feet at short intervals 
with an average speed of 550 feet per minute. Such 
vibrations transmitted to halls or neighboring rooms 
are due entirely to the displacement of the air. 

In installations where the air-intake of the engine is 


located in the engine-room, a certain compensation is 
secured, at the period of suction, between the quantity 
of air expelled on the forward stroke of the piston and 
the quantity of air drawn into the cylinder. From this 
it follows that the vibration caused by the movement 
of the air is felt less and occurs but once for two revolu- 
tions of the engine. 

This phenomenon is very manifest in narrow rooms 
in which the engine happens to be installed near glass 
windows. By reason of the elasticity of the glass, the 
windows acquire a vibratory movement corresponding 
in period with half the number of revolutions of the 
engine. It follows from the preceding that, in order to 
do away with the air vibration occasioned by the piston 
in drawing in and forcing out air in an enclosed space, 
openings should be provided for the entrance of large 
quantities of air, or a sufficient supply of air should 
be forced in by means of a fan. 

The author ends this section with the advice that all 
pipes in general and the exhaust-pipe in particular be 
insulated from the foundation and from the walls 
through which they pass as well as from the ground, 
as metal pipes are good conductors of sound and liable 
to carry to some distance from the engine the sounds 
of the moving parts. 

Exhaust Noises. — Among the most difficult noises to 
muffle is that of the exhaust. Indeed, it is the exhaust 
above all that betrays the gas-engine by its discharge to 
the exterior through the exhaust-pipe. The most com- 
monly employed means for rendering the exhaust less 



perceptible consists in extending the pipe upward as 
far as possible, even to the height of the roof. This is 
an easy way out of the difficulty; but it has a bad effect 
on the operation of the engine. It reduces the power 
generated and increases the consumption, as will be ex- 
plained in a special paragraph. 

Expansion-boxes, more commonly called exhaust- 
mufflers, considerably deaden the noise of explosion by 


Fig. 56.— Exhaust -muffler. 

the use of two or three successive receptacles. But this 
remedy is attended with the same faults that mark the 
use of extremely long pipes. The best plan is to mount 
a single exhaust-muffler near the discharge of the en- 
gine in the engine-room itself, where it will serve at 
least the purpose of localizing the sound. 

The employment of pipes of sufficiently large cross- 
section to constitute expansion-boxes in themselves will 
also muffle the exhaust. A more complete solution of 
the problem is obtained by causing the exhaust-pipe. 


after leaving the muffler, to discharge into a masonry 
trough having a volume equal to twelve times that of 
the engine-cylinder (Fig. 56). This trough should 
be divided into two parts, separated by a horizontal 
iron grating. Into the lower part, which is emptv, the 
exhaust-pipe discharges; in the upper part, paving- 
blocks or hard stones not likely to crumble with the 
heat, are placed. Between this layer of stones and the 
cover it is advisable to leave a space equal to the first. 
Here the gases may expand after having been divided 
into many parts in passing through the spaces left be- 
tween adjacent stones. The trough should not be 
closed by a rigid cover; for, although efficient muffling 
may be attained, certain disadvantages are neverthe- 
less encountered. It may happen that in a badly regu- 
lated engine, unburnt gases mav be discharged into this 
trough, forming an explosive mixture which will be 
ignited bv the next explosion, causing considerable 
damage. Still, the explosion will be less dangerous 
than noisy. It may be mentioned in passing that this 
disadvantage occurs rarely. 

A second arrangement consists in superposing the 
end of the exhaust-pipe upon a casing of suitable size, 
which casing is partitioned off by several perforated 
baffle-plates. This casing is preferably made of wood, 
lined with metal, so that it will not be resonant. The 
size of the casing, the number of partitions and their 
perforations, and the manner of disposing the parti- 
lions have much to do with the result to be obtained. 
Here igain the experience of the expert is of use. 



Various other systems are employed, depending upon 
the particular circumstances of each case. Among 
these systems may be mentioned those in which the pipe 
is forked at its end to form either a yoke (Fig. 57) or 
a double curve, each branch of which terminates in a 
muffler (Fig. 58). 

It should be observed that, under ordinary conditions, 
noises heard as hissing sounds are often due to the 

r *\ 




Fig. 57. 

Two types of exhaust-mufflers. 

Fie;. 58. 

presence of projections, or to distortion of the pipes 
near the discharge opening. Consequently, in connect- 
ing the pipes, care should be taken that the joints or 
seams have no interior projections. Occasionally, 
water may be injected into the exhaust-muffler in order 
to condense the vapors of the exhaust, the result being 
a deadening of the noises; but in order to be truly effi- 
cient this method should be employed with discretion, 
for which reason the advice of an expert is of value. 



Circulation of water in explosion-engines is one of 
the essentials of their perfect operation. Two special 
cases are encountered. In the one the jacket of the en- 
gine is supplied with running water; in the other, reser- 
voirs are employed, the circulation being effected 
simply by the difference in specific gravity in a thermo- 
siphon apparatus. Coolers are also used. 

Running Water. — A water-jacket fed from a con- 
stant source of running water, such as the water mains 
of a town, is certainly productive of the best results, the 
supply, moreover, being easily regulated; but the sys- 
tem is not widely used because the water runs away and 
is entirely lost. If running water be employed, the out- 
let of the jacket is so disposed that the water gushes out 
immediately on leaving the cylinder, and that the flow 
is visible and accessible, in order that the temperature 
may be tested by the hand. Apart from the relatively 
great cost of water in towns, the use of running water 
is objectionable on account of its chemical composi- 
tion. Though it may be clear and limpid, it frequently 
contains lime salts, carbonates, sulphates, and silicates 
which are precipitated by reason of the sudden change 
of temperature to which the water is subjected as it 




comes into contact with the walls of the cylinder. That 
part of the water-jacket surrounding the head or explo- 
sion-chamber, where the temperature is necessarily the 
highest, becomes literally covered with calcareous in- 
crustations, which are the more harmful because they 
are bad conductors of heat and because they reduce and 
even obstruct the passage exactly at the point where the 
water must circulate most freely to do any good, If the 
circulating water be pumped into the jacket, it is pref- 
erable, wherever possible, to use cistern water, which is 
not likely to contain lime salts in suspension. If river 
water he used, it should be free from the objections 
already mentioned, which are all the more grave if the 
water be muddy, as sometimes happens. The water- 
jacket can be easily freed from all non-adhering de- 
posits by flushing it periodically through the medium 
of a conveniently placed cock. It is always preferable 
to pass the water through a reservoir where its impuri- 
ties can settle, before it flows to the cylinder. In the 
case considered, the water usually has an average tem- 
perature of 54 to 60 degrees F., under which condition 
the hourly flow should be at least 5 }/* gallons per horse- 
power per hour, the temperature rising at the outlet- 
pipe of the cylinder to 140 and 158 degrees F., which 
should not be surpassed. However, in engines working 
with high compression, 104 to 122 degrees F. should 
not be exceeded. 

If the water-jacket be fed by a reservoir, it is essen- 
tial that the reservoir comply with the following con- 



In horizontal engines the water-inlet is always 
located in the base of the cylinder, while the outlet is 
located at the top. By providing the inlet-pipe extend- 
ing to the cylinder with a cock, the circulation of water 
can be regulated to correspond with the work per- 
formed by the engine. Another cock at the end of the 
outlet-pipe near the reservoir serves, in conjunction 

Fig. 59.— Thermo -syphon cooling system. 

with the first, to arrest the circulating water. When the 
weather is very cold or when the cylinder must be 
repaired, these two cocks may be closed, and the pipe 
and water-jacket of the cylinder drained by means of 
the drain-cock V (Fig. 59), mounted at the inlet of the 
engine's water-jacket. In order that the pressure of 
the atmosphere may not prevent the flowing of the 
water, the highest part of the pipe is provided with a 
small tube, T, communicating with the atmosphere. 
On account of the importance of preventing losses 


of the charge in the pipes the author recommends the 
utilization of sluice-valves of the type shown in Fig. 
60, instead of the usual cone or plug type. 

Water-Tanks. — The reservoir is mounted in such a 
way that its base is flush with the top of the cylinder; it 
should be as near as possible to the cylinder in order to 
obviate the use of long inlet and return pipes. This 
fact, however, does not necessarily render it advisable 
to place the reservoir in the engine-room; for such a 
disposition is doubly disadvantageous in so far as it 
does not permit a sufficiently rapid cooling of the cir- 
culating water by reason of the high temperature of the 


surrounding air, and in so far as it is liable to cause the 
formation of vapors which injuriously affect the en- 
gine. Consequently, the reservoir should be placed in 
as cool a place as possible, preferably even in the open 
air; for the water is not likely to freeze, except when 
it has been allowed to stand for a considerable time. 
The reservoir should be left uncovered so as to facili- 
tate cooling by the liberation of the vapors formed on 
the surface of the water. 

Circulation being effected solely by the difference 
in specific gravity or density between the warmer water 
emerging from the cylinder and the cooler water which 
Hows in from the reservoir, the slightest obstruction 
will impede the flow, Hence, the cross-section of the 
pipes should not be less than that of the inlet and outlet 
openings of the cylinder of the engine. Good circula- 
tion cannot be attained if the water must overcome in- 
clines or obstacles in the pipes themselves. Instead of 
elbows, long curves of great radius, limited to the 
smallest possible number, should be employed. This is 
particularly true of the return-pipe extending from 
the cylinder back to the reservoir. For this pipe a 
minimum incline of 10 to 15 per cent, should be al- 
lowed, in order that the water may run up into the 
reservoir. The height of the water in the reservoir 
should be from 2 to 4 inches above the discharge of the 
return-pipe. In order to maintain this level it is advis- 
able to use some automatic device such as a float-valve, 
in which case the reservoir should not be allowed to 
become too full. 



The size of a reservoir is determined by the engine; 
it should be large enough to. enable the engine to run 

Fro. 61. — Correct arrangement of tanks and piping. 

smoothly at its maximum load for several hours con- 
secutively. Under these conditions, the reservoir 




should have a capacity of 45 to 55 gallons per horse- 
power for engines with " hit-and-miss " admission, and 
55 to 65 gallons for engines controlled by variable ad- 
mission. It is not advisable to employ reservoirs hav- 

ing a capacity of more than 330 to 440 gallons, the 
usual diameter being about 3 feet. 

If the power of the engine be such that several 
reservoirs are necessary, then the reservoirs should be 
connected in such a manner that the top of the first 
communicates with the bottom of the next and so on, 


io 5 

the first reservoir receiving the water as it comes from 
the cylinder (Fig. 61). 

Intercommunication of the reservoirs by means of a 
common top tube (a) is objectionable; and simul- 
taneous intercommunication at top and bottom (a and 
b) is ineffective, so far as one of the reservoirs is con- 
cerned (Fig. 62). 

The reservoirs are true thermo-siphons. Conse- 
quently the water should be methodically circulated; 
in other words, the hottest water, flowing from the en- 

Fic». 63. Tanks connected by inclined pipes. 

gine into the top of the first reservoir and having, for 
example, a temperature of 104 degrees F., is cooled off 
to 86 degrees F. and drops to the bottom of the reser- 
voir, thence to be driven, at a temperature sensibly 


equal to 86 degrees F., to the second reservoir, where a 
' further cooling of 18 degrees F. takes place. In pass- 
ing on to the following reservoirs the temperature is 
still further lowered, until the water finally reaches its 
minimum temperature, after which it flows back to the 

In order to effect this cooling, the reservoirs can be 
connected in several ways. The most common method, 
as shown in Fig. 63, consists in connecting the reser- 
voirs by oblique pipes. This is open to criticism, how- 

Fifi. 64.— Circu luting pump with by-pass. 

ever, since leakage occurs, caused by the employment 
of elbows which retard the circulation. A less cum- 
brous and more efficient method of connection consists 
in joining the reservoirs by a single pipe at the top, as 
shown in Fig. 61 ; but care must be taken to extend this 
pipe at the point of its entrance into the adjoining 
reservoir by means of a downwardly projecting exten- 
sion, or to fit its discharge-end with a box, closed by a 
single partition, open at the bottom. 


In order to prevent incrustation of the wafer-jacket 
surrounding the cylinder, a pound of soda per 17 cubic 
feet of the reservoir capacity is monthly introduced, 
and the jacket flushed weekly by a cock conveniently 
mounted near the cylinder (Fig. 59). The jacket is 
thus purged of calcareous sediments, which are pre- 
vented by the soda from adhering to the metal. The 
flushing-cock mentioned also serves to drain the water- 
jacket of the cylinder in case of intense or persistent 
cold, which would certainly freeze the water in the 
jacket, thereby cracking the cylinder or the exposed 

In order to regulate the circulation of the water in 
accordance with the work performed by the engine, a 
cock should be fitted to the water supply pipe at a con- 
venient place. 

In engines of large size, driven at full load for long 
periods, cooling by natural circulation is often in- 
adequate. In such cases, circulation is quickened bv a 
small rotary or reciprocating pump, driven from the 
engine itself and fitted with a by-pass provided with a 
cock. This arrangement permits the renewal of the 
natural thermo-siphon circulation in case of accident 
to the pump (Fig. 64). 

Coolers. —The arrangement which is illustrated in 
Fig. 65, and which has the merit of simplicity, will he- 
found of service in cooling the water. It comprises a 
tank B surmounted by a set of trays E, formed of frames 
to which iron rods are secured, spaced 1 to 2 feet apart, 
so as to form superimposed series separated by 1^ to 


2 L ; feet. On these trays bundles of tree branches are 
placed, The cold water at the bottom of the tank is 
forced by the pump P into the water-jacket, from 
which it emerges hot, and flows through the pipe T, 

Fin. 65, — Waler-coolcr in which tret branches are employed. 

which ends in a sprinkler G, formed of communicat- 
ing tubes and perforated with a sufficient number of 
holes to enable the water to fall upon the trays in many 
drops. Thus finely divided, the water falls from one 
tray to another, retarded as it descends by the bundles 



of tree branches. It finally reaches the tank in a very 
cold condition and is then ready to be pumped to the 
engine. Birch branches are to be preferred on account 
of their tenuity. 

Great care should be taken to cover the tank with 
a sheet-metal closure in order to prevent twigs and 

Fig. 66. — Fan-cooler. 

foreign bodies from entering and from being drawn 
into the pump. 

In the following table the dimensions of an operative 
apparatus of this kind are given, — an apparatus, more- 
over, that may be constructed of wood or of iron: — 


Volume in 


cubic ft. 


IO5 1 






350 1 







Height of 



! 8.1' 

I 9-i' 

• Pump — Capacity 
in gals, per min. 

4.9' x 4.9' 
5.2' x 5.2' 

m ^/ v m mm 

W x W, 

6.6' x 6.6' 

,. . 4 X / . 4 

1 l6.7I 

' 18.69 




In order that the water may not drop to one side, the 
base of the apparatus should be made 10 to 12 inches 
less in width than the tank. 

The size of these apparatus may be considerably re- 
duced by constructing them in the form of closed chests, 
into the bottom of which air injected by means 
of fans in order to accelerate cooling (Fig. 66). 



Lubrication is a subject that should be studied by 
every gas-engine user. .So far as the piston is con- 
cerned it is a matter of the utmost importance. The 
piston does its work under very peculiar conditions. 
It is driven at great linear velocities; and it is, more- 
over, subjected to high temperatures which have noth- 
ing in common with good lubrication if care be not 

The piston is the essential, vital element of an en- 
gine. Upon its freedom from leakage depends the 
maintenance of a proper compression, and, conse- 
quently, the production of power and economical con- 
sumption. As it travels forward and as it recedes from 
the explosion-chamber, it uncovers more and more of 
the frictional surface constituting the interior wall of 
the cylinder. This surface, as a result, is regularly 
brought into contact with the ignited, expanding gases 
after each explosion. For this reason the oil which 
covers the wall is constantly subjected to high tempera- 
tures, by which it is likely to be volatilized and burned. 
Therefore, the first condition to be fulfilled in properly 
lubricating the piston is a constant and regular sup- 
ply of oil. 



Quality of Oils. — For cylinder lubrication only the 
very best oils should be used; perfect lubrication is of 
such importance that cost should not be considered. 
Besides, the surplus oil which is usually caught in the 
drip-pan is bv no means lost. After having been fil- 
tered it can be used for lubricating the bearings of the 
crank, the cam-shaft, and like parts. 

Cylinder-oil should be exceedingly pure, free from 
acids, and composed of hydrocarbons that leave no resi- 
due after combustion. Only mineral oils, therefore, 
are suitable for the purpose. Those oils should be 
selected which, with a maximum of viscosity, are 
capable of withstanding great heat without volatilizing 
or burning. The point at which a good cylinder-oil 
ignites should not be lower than 535 degrees F. 

Whether an oil possesses this essential quality is 
easily enough ascertained in practice without resort- 
ing to laboratory tests. All that is necessary is to heat 
the oil in a metal vessel or a porcelain dish. In order 
that the temperature may be uniform the vessel is 
shielded from the direct flame by interposing a piece 
of sheet metal or a layer of dry sand. As soon as gases 
begin to arise a lighted match is held over the oil. 
When the gases are ignited the thermometer reading is 
taken, the instrument being immersed in the oil. The 
temperature recorded is that corresponding with the 
point of ignition. 

For cylinder lubrication American mineral oil is 
preferable to Russian oil. The specific gravity should 
lie somewhere between .886 and .889 at 70 degrees F. 



Oil of this quality begins to evaporate at about 365 
degrees F. Ignition occurs at 535 degrees F. The 
point of complete combustibility lies between 625 and 
645 degree F. Oil of this quality solidifies at 39 or 
41 degrees F. Its color is a reddish yellow with a 
greenish fluorescence. Compared with water its degree 
of viscosity lies between 11.5 and 12.5 at a tempera- 
ture of 140 degrees F. 

Before lubricating other parts of the engine with 
oil that has been used for the piston, heavy particles 
and foreign matter, such as dust, bearing incrusta- 
tions, and the like, should be filtered out. The piston- 
pivot and the connecting-rod head are preferably 
lubricated with fresh oil, because their constant move- 
ment renders inspection difficult and the control of 
lubrication irksome. A good, industrial mineral oil 
of usual market quality will be found satisfactory. 

In order to bring home the importance of employ- 
ing good cylinder-oil and of proper lubrication the 
author can only state that in his personal experience he 
has frequently detected losses varying from 10 to 15 
per cent, in the power developed by engines poorly 

Types of Lubricators. — Among the more common 
apparatus employed for automatically lubricating the 
cylinder, the author mentions an English oiler of the 
type pictured in Fig. 67 which is driven simply by 
a belt from the intermediary shaft, and which rotates 
the pulley P secured on the shaft a of the apparatus, 
at a very slow speed. The shaft a is provided at its 


end with a small crank, from which a small iron arm 
f is suspended, which arm dips in the oil contained in 
the cup G of the oiler. When the shaft a is turned this 
arm, as it sweeps through the oil-bath, collects a certain 
quantity of oil which it deposits on the collector 
b. From this spindle the oil passes through an out- 
let-pipe opening into the bottom of the oiler, and 
thence to the cylinder. The entire apparatus is closed 

Fig. 67. — An automatic English .oiler. 
by a cover D which can be easily removed in order to 
ascertain the quantity of oil still remaining in the 
apparatus. Many other systems are utilized which, 
like the one that has been described, enable the feed to 
be controlled. Often small force-pumps are employed 
as cylinder-lubricators. Whatever may be the type 
selected, preference should be given to that in which 
the feed is visible (Fig. 68). 

If the oil be fed under pressure the cylinder is more 
constantly lubricated. Pressure-lubricators are nowa- 
days widely used on large engines. It is advisable to 


add a little salt to the water contained in sight-feed 
lubricators so that the drop of oil is easily freed. 

These oil-pumps are provided with small check- 
valves at their outlets as well as at the inlets of cylin- 
ders. In order that pressure-lubricators may operate 
perfectly they should be regularly inspected and the 
check-valves ground from time to time. 

The lubrication of the crank-shaft and of the two 
connecting-rod heads should receive every attention. 

-Sight-feed I ubrica ting-pump. 

Lubricating devices should be employed which, 
besides being efficient, do not necessitate the stopping 
of the engine in order to oil the bearings. The foot of 
the connecting-rod at the point where it is pivoted to 
the piston is generally lubricated with cylinder-oil 
which is supplied by a tube mounted in the proper 
place across the piston-wall (Fig. 69). This ar- 
rangement may be adequate enough for small engines; 
but it is not sufficiently sure for engines of considerable 
size. An independent lubricating system should be 
employed, lubrication being effected either by a 

n6 G^ 

splasher mounted in front of the cylinder or by a lubri- 
cator secured to the connecting-rod by which the pivot 
is lubricated through the medium of a small tube sup- 
plying special oil {Fig. 21). The head of the con- 
necting-rod where it meets the crank, must also be 
carefully lubricated because of the important nature 
of the work which it must perform, and because of the 
shocks to which it is subjected at each explosion. For 

Fig. 69. — Method of oiling the piston and end of the connecting-rod. 
motors of high power the system which seems to give 
most satisfactory results is that illustrated in Fig. 70. 
The arrangement there shown consists of an annular 
vessel secured at one side of the crank and turning con- 
centrically on its axis ; the vessel being connected with a 
long tube extending into a channel formed in the crank 
and discharging at the surface of the crank-pin within 
the bearing at the head of the connecting-rod. An 
adjustable sight-feed lubricator conducts the oil along 
a pipe to the vessel. Turning with the shaft, the ves- 


sel retains the oil in the periphery so that the feed in 
the previously mentioned channel in the connecting- 
rod head, is constant. 

The main crank-shaft bearings are more easily lubri- 
cated. Among the systems commonly used with good 
results may be mentioned that shown in Fig. 71, in 
which the half section represents a small tube starting 


from the bearing and terminating in the interior of an 
oil recess or reservoir cast integrally with the bearing- 
cap. This reservoir is rilled up to the level of the tube 
opening. A piece of cotton waste held on a small iron 
wire is inserted in the tube, part of the cotton being 
allowed to hang down in the reservoir. This cotton 
serves as a kind of siphon and feeds the bearing by 
capillary attraction with a constant quantity of oil, the 
supply being regulated by varying the thickness of the 


cotton. When the motor is stopped, the cotton should 
be removed in order that oil-feeding may not use- 
lessly continue. Glass, sight-feed lubricators with 
stop-cocks, are very often used on crank-shafts. They 
are cleaner and much more easily regulated. Of all 
shaft-bearing lubricators, those which are most to be 
recommended are of the revolving-ring type (Fig, 
72). They presuppose, however, bearings of large 

size and a special arrangement of bushings which ren- 
ders their application somewhat expensive. Further- 
more, the revolving- ring system can hardly be used in 
connection with engines of less than 20 horse-power. 
Since the system is applied almost exclusively to 
dynamo-shafts, it need not here be described in detail. 
As its name indicates, it consists of a metal ring having 
a diameter larger than that part of the shaft from 
which it is suspended and by which it is rotated. The 
lower part of the ring is immersed in an oil bath so 


that a certain quantity of lubricant is continually trans- 
ferred to the shaft. 

The revolving ring bearing should be fitted with a 
drain-cock and a glass tube in order to control the 
level of the oil in the bearing. 

Many manufacturers have adopted lubricating de- 


Fir,. 72.— Ring ly] 

vices for valve-stems, and especially for exhaust-valves. 
The system adopted consists of a small tube curved in 
any convenient direction and discharging in the stem- 
guide. The free end is provided with a plug. A few 
drops of petroleum arc introduced once or twice a day. 
The lubrication of an engine entails certain difficul- 
ties which are easily overcome. One of these is the 


splashing of oil by the connecting-rod head. In order 
that this splashed oil may be collected in the base 
of the engine a suitably curved sheet-metal guard is 
mounted over the crank. A more serious difficulty 
is presented when the oil from a crank-bearing finds 
its way to the hub of the fly-wheel, whence it is driven 
by the centrifugal force to the rim. The oil is not only 
splashed against the walls o.f the engine-room, but it 
also destroys the adhesion of the belt if the fly-wheel 


Fig. 73.— Shaft with oii-puard. 

be employed as a pulley, In order to overcome this 
objection the oil is prevented from spreading along the 
shaft by means of a circular guard (Fig. 73) mounted 
on that portion of the shaft toward the interior of the 

The problem of lubrication is of particular im- 
portance if the engine is driven for several days at 
a time without a stop. This happens in the case of 
mill and shop engines. Lubricators of large volume 
or lubricators which can be readily filled without stop- 
ping the engine should be employed. 



General Care.— Gas-engines, as well as most ma- 
chines in general, should be kept in perfect condition. 
Cleanliness, even in the case of parts of secondary im- 
portance, is indispensable. L'npainted and polished 
surfaces such as the shaft of the engine, the distribut- 
ing cam-shafts, the levers, the connecting-rod and the 
like, should be kept in a condition equal to that when 
they were new. The absence of all traces of rust or 
corrosion in these parts affords sufficient evidence of 
the care taken of the invisible members such as the 
piston, the valves, ignition devices, and the like. 

Lubrication. — The rubbing surfaces of a gas-engine 
should be regularly and perfectly lubricated. The 
absence of lost motion and backlash in the bearings, 
guides, and joints is of particular importance not only 
because of its influence on steady and silent running, 
but also on the power developed and on the consump- 
tion. As we have already seen in the chapter on lubri- 
cation, a special quality of oil should be employed for 
the lubrication of the cylinder. The feed of the lubri- 
cator supplying this most vital part of the engine is so 
regulated that it meets the actual requirements with 
the utmost nicety possible. In a subsequent chapter. 


in which faulty operation will be discussed, it will be 
shown how too much and too little oil may cause seri- 
ous trouble. 

Tightness of the Cylinder.— The amount of power 
developed depends principally on the degree of com- 
pression to which the explosive mixture is subjected. 
The economical operation of the engine depends in 
general upon perfect compression. It is, therefore, 
necessary to keep those parts in good order upon which 
the tightness of the cylinder depends. These parts are 
the piston, the valves, and their joints, and the igni- 
tion devices whether they be of the hot-tube or elec- 
trical variety. In order to prevent leakage at the pis- 
ton, the rings should be protected from all wear. It 
is of the utmost importance that the surfaces both of 
the piston and of the cylinder, be highly polished so 
that binding cannot occur. In cleansing the cylinder, 
emery paper or abrasive powder should not be em- 
ployed; for the slightest particle of abrasive between 
the surfaces in contact will surely cause leakage. The 
oil and dirt, which is turned black by friction and 
which may adhere to the piston rings, should be 
washed awav with petroleum. Similarly the other 
parts of the cylinder should be cleaned to which burnt 
oil tends to adhere. 

Valve-Regrinding.— The valves should be regu- 
larly ground. Even in special cases where they may 
show no trace of rapid wear they should be removed 
at least every month. In order to avoid any accident, 
care should be taken in adjusting the valves after the 



cap has been unbolted not to introduce a candle or a 
lighted match either in the valve-chambers or in the 
cylinder, without first closing the gas-cock. Further- 
more, a few turns should be given to the engine, in 
order to drive out any explosive mixture that may still 
remain in the cylinder or the connected passages. The 
exhaust-valve, by reason of the high temperature to 
which the disk and the seat are subjected, should re- 
ceive special attention. The valve should be ground 
on its seat every two or three months at least, depend- 
ing upon the load of the engine. 

Bearings and Crosshead.— The bushings of the en- 
gine shaft should always be held tightlv in place. The 
looseness to which they are liable, particularly in gas- 
engines on account of the sharp explosions, tends to 
unscrew the nuts and to hasten the wear of the brass. 
which is the result of frequent tightening. The slight- 
est play in the bearings of the engine-shaft as well as 
in the bearings of connecting-rods increases the sound 
that engines naturally produce. 

Governor. — The governor should receive careful at- 
tention sit far as its cleanliness is concerned; for if its 
operation is not easy it is apt to become " lazy " ;iiui 
to lose its sensitiveness. If the governor be of the ball 
type, or of the conical pendulum type operated by 
centrifugal force, it is well to lubricate each joint with- 
out excess of oil. In order to prevent the accumula- 
tion and the solidification of oil, the governor should 
be lubricated from time to time with petroleum. If 
the governor is actuated by inertia, which is the case 


in most engines of the hit-and-miss variety, it needs 
less care; still, it is advisable to keep the contact at 
which the thrust takes place well oiled. 

The operation of any of these governors is usually 
controlled by the tension of a spring, or by a counter- 
weight. In order to increase the speed of the engine, 
or in other words, to increase the number of admissions 
of gas in a given time, all that is usually necessary is 
to tighten up the spring, or to change the position of 
the counterweight. It should be possible to effect 
this adjustment while the engine is running in such a 
manner that the speed can be easily changed. 

Joints. — In most well-built engines the caps of the 
valve-chests and other removable parts are secured 
" metal on metal " without interposing special joints. 
In other words, the surfaces are themselves sufficiently 
cohesive to insure perfect tightness. In engines which 
are not of this class, asbestos joints are very frequently 
employed, particularly at the exhaust-valve cap and 
the suction-valve. 

In some engines, where for any reason it is necessary 
f requently to detach the caps, certain precautions should 
be taken to protect the joints so that they may not be 
exposed to deterioration whenever they are removed. 
For this purpose, they are first immersed in water in 
order to be softened, then dried and washed with olive 
or linseed oil on the side upon which they rest in the 
engine. On the cap side they are dusted with talcum 
or with graphite. Treated in this manner, the joint 
will adhere on one side and will be easily released on 



the other. Joints that are liable to come in contact 
with the gases in the explosion-chamber should be free 
from all projections toward the interior of the cylin- 
der; for during compression these uncooled projections 
may become incandescent and may thus cause prema- 
tura ignition. As a general rule when the cap is 
placed in position the joint should be retightencd alter 
a certain time, when the surfaces have become suffi- 
ciently heated. In order to tighten the joints the bolts 
and nuts should not be oiled; otherwise the removal of 
the cap becomes difficult. 

Water Circulation.— In a previous chapter, the im- 
portance of the water circulation and the necessity of 
keeping the cylinder-jacket hot, have been sufficiently 
dwelt upon. As the cvlinder tends to become hotter 
with an increase in the load, because of the greater fre- 
quency of explosions, it is advisable to regulate ihe 
flow of the water in order to prevent its becoming more 
than sufficient in quantity when the engine is lightly 
loaded; for under these conditions the cylinder will be 
cold and the explosive mixture will be badly utilized. 
A suitable temperature of 140 to 158 degrees F. is 
easily maintained by adjusting the circulation of the 
water. This can be accomplished by providing the 
water-inlet pipe leading to the cylinder with a cock 
which can be opened more or less, as may be necessary. 
The temperature of 140 to 158 degrees F. which has 
been mentioned may, at first blush, seem rather high, 
because it would be impossible to keep the hand on the 
outlet-pipe. The cylinder, however, will not become 


overheated so long as it is possible to hold the hand 
beneath the jacket near the water-inlet. This relates 
only to engines having a compression of 50 to 100 lbs. 
per square inch. For engines of higher compression, 
a lower running temperature will be safer. On this 
matter the instructions of the engine maker should be 
carried out. 

Adjustment. — Gas-engines, at least those which arc 
built by trustworthy firms, are always put to the brake 
test before they are sent from the shops, and are ad- 
justed to meet the requirements of maximum efficiency. 
But since the nature and quality of gas necessarily 
vary with each city, it is evident that an engine 
adjusted to develop a certain horse-power with a gas 
of. a certain richness, may not fulfil all expectations 
if it is fed with a gas less rich, less pure, hotter, and 
the like. The altitude also has some influence on the 
efficiency of the engine. As it increases, the density of 
the mixture diminishes; that is to say, for the same vol- 
ume the engine is using a smaller amount. From this 
it follows that a gas-engine ought to be adjusted as a 
general rule on the spot where it is to be used. 

The fulfilment of this condition is particularly im- 
portant in the case of explosion-engines, because an 
advancement or retardation of only one-half a second 
Jn igniting the explosive mixture will cause a consid- 
erable loss in useful work. From this it would follow 
that gas-engines should be periodically inspected in 
order that they may operate with the highest efficiency 
and economy. As in the case of steam-engines, it is 


advisable to take indicator records which afford con- 
clusive evidence of the perturbations to which every 
engine is subject after having run for some time. 

Most gas-engine users either have no indicating in- 
struments at their disposal or else are not sufficiently 
versed in their employment and the interpretation of 
their records to study perturbations by their means. 
For this reason the advice of experts should be sought, 
— men who understand the meaning of the diagrams 
taken and who are able by their means to effect a con- 
siderable saving in gas. 



The first step which is taken in starting an engine 
driven by street-gas is, naturally, the opening of the 
meter-cock and the valves between the meter and 
the engine. When the gas has reached the engine, the 
rubber bags will swell up and the anti-pulsator dia- 
phragm will be forced out. The drain-cock of the gas- 
pipe is then opened. In order to ascertain whether 
the flow of gas is pure, a match is applied to the outlet 
of the cock. The flame is allowed to burn until it 
changes from its original blue color to a brilliant 

If the hot-tube system of ignition be employed, the 
Bunsen burner is ignited, care being taken that the 
flame emerging from the tube is blue in color. If 
necessary the admission of air to the burner is regu- 
lated by the usual adjusting-sleeve. A white or smoky 
flame indicates an insufficient supply of air to the 
burner. A characteristic sooty odor is still other evi- 
dence of the same fact. Sometimes a white flame may 
be produced by the ignition of the gas at the opening 
of the adjusting-sleeve. A blue or greenish flame is 
that which has the highest temperature and is the one 


which should, 

ten minutes arc require 

re, be obtained. About five 

) heat i 


up the tube, owing to 
the material of which it is made. When the proper 
temperature has been attained the tube becomes a daz- 
zling cherry red in color. While the tube is being 
heated up, it is well to determine whether the engine 
is properly lubricated and all the cups and oil reser- 
voirs are duly filled up. The cotton waste of the 
lubricators should be properly immersed, and the drip 
lubricators examined to determine whether they are 
supplying their normal quantity of oil. 

The regulating-levers of the valves should be oper- 
ated in order to ascertain whether the valves drop upon 
their seats as they should. The stem of the exhaust- 
valve should be lubricated with a few drops of petro- 

If the ignition system employed be of the electric 
type, with batteries and coils, tests should be made to 
determine whether the current passes at the proper 
time on completing the circuit with the contact 
mounted on the intermediary shaft. This contact 
should produce the characteristic hum caused by the 
operation of the coil. 

If a magneto be used in connection with the igni- 
tion apparatus, its inspection need not be undertaken 
whenever the engine is started, because it is not so 
likely to be deranged. Still, it is advisable, as in the 
case of ignition by induction-coils, to set in position 
the device which retards the production of the spark. 
This precaution is necessary in order to avoid a prema- 


ture explosion, liable to cause a sharp backward revo- 
lution of the fly-wheel. 

After the ignition apparatus and the lubricators have 
been thus inspected, the engine is adjusted with the 
piston at the starting position, which is generally indi- 
cated by a mark on the cam-shaft. The starting posi- 
tion corresponds with the explosion cycle and is gen- 
erally at an angle of 40 to 60 degrees formed by the 
crank above the horizontal and toward the rear of the 
engine. The gas-cock is opened to the proper mark, 
usually shown on a small dial. If there be no mark, 
the cock is slowly opened in order that no premature 
explosion mav be caused by an excess of gas. 

The steps outlined in the foregoing are those which 
must be taken with all motors. Each system, how- 
ever, necessitates peculiar precautions, which are 
usually given in detailed directions furnished by the 

As a general rule the engines are provided on their 
intermediary shafts with a "relief" or "half-com- 
pression " cam. By means of this cam the fly-wheel 
can be turned several times without the necessity of 
overcoming the resistance due to complete compres- 
sion. Care should be taken, however, not to release 
the cam until the engine has reached a speed sufficient 
to overcome this resistance. 

Engines of considerable size are commonly provided 
with an automatic starting appliance. In order to 
manipulate the parts of which this appliance is com- 
posed, the directions furnished by the manufacturer 




must be followed. Particularly is this true of auto- 
matic starters comprising a hand-pump by means of 
which an explosive mixture is compressed, — true be- 
cause in the interests of safety great care must be taken. 

The tightness and free operation of the valves or 
clacks which are intended to prevent back firing 
toward the pump should be made the subject of care- 
ful investigation. Otherwise, the piston of the pump 
is likely to receive a sudden shock when back firing oc- 

When the engine has been idle for several days, it 
is advisable, before starting, to give it several turns 
(without gas) in order to be sure that all its parts 
operate normally. The same precaution should be 
taken in starting an engine, if a first attempt has failed, 
in order to evacuate imperfect mixtures that may be 
left in the cylinder. Before this test is made, the gas- 
cock should, of course, be closed in order to prevent 
an untimely explosion. It is advisable in starting an 
engine not to bend the body over the ignition-tube, 
because the tube is likely to break and to scatter dan- 
gerous fragments. 

Under no condition whatever should the fly-wheel 
be turned by placing the foot upon the spokes. All 
that should be done is to set it in motion by applying 
the hand to the rim. 

Care During Operation.— When the engine has ac- 
quired its normal speed, the governor should be looked 
after in order that its free operation may be assured 
and that all possibility of racing may be prevented. 


After the engine has been running normally for a time, 
the cocks of the water circulation system should be 
manipulated in order to adjust the supply of water to 
the work performed by the engine. In other words 
the cylinder should be kept hot, but not burning, as 
previously explained in the paragraph in which the 
water-jacket is discussed. The maintenance of a suit- 
able temperature is extremely important so far as 
economy is concerned. All the bearings should be in- 
spected in order that hot boxes may be obviated. 

Stopping the Engine.— The steps to be taken in 
stopping the engine are the following: 

i. Stopping the various machines driven by the en- 
gine, — a practice which is followed in the case of all 
motors ; 

2. Throwing out the driving-pulley of the engine 
itself, if there be one; 

3. Closing the cock between the meter and the gas- 
bags in order to prevent the escape of gas and the use- 
less stretching of the rubber of the bags or of the anti- 
pulsating devices; 

4. Actuating the half-compression or relief cam as 
the motor slows down, in order to prevent the recoil 
due to the compression; 

5. Closing the gas-admission cock; 

6. Shutting off the supply of oil of free flowing 
lubricators, and lifting out the cotton from the others. 

If the engine be used to drive a dynamo, particularly 
a dvnamo provided with metal brushes, the precaution 
should be taken of lifting the brushes before the en- 


gine is stopped in order to prevent their injury by a 
return movement of the armature-shaft; 

7. Shutting off the cooling-water cock if running 
water is used. 

If the engine is exposed to great cold, the freezing 
of the water in the jacket is prevented while the engine 
is at rest, either by draining the jacket entirely, or by 
arranging a gas jet or a burner beneath the cylinder 
for the purpose of causing the water to circulate. If 
such a burner be used the cocks of the water supply 
pipe should, of course, be left open. 




In this chapter will be discussed certain perturba- 
tions which affect the operations of gas-engines to a 
more marked degree than lack of care in their con- 
struction. In previous chapters defects in operation 
due to various causes have been dwelt upon, such as 
objectionable methods in the construction of an engine, 
ill-advised combination of parts, defects of installation, 
and the like; and an attempt has been made to deter- 
mine in each case the conditions which must be ful- 
filled by the engine in order to secure efficiency and 
economy at a normal load. 

Difficulties in Starting. — The preliminary precau- 
tions to be taken in starting an engine having been in- 
dicated, it is to be assumed that the advice given has 
been followed. Nevertheless various causes may pre- 
vent the starting of the engine. 

Faulty Compression. — Defective compression, as a 
general rule, prevents the ignition of the explosive 
mixture. Whether or not the compression be imper- 
fect can be ascertained by moving the piston back to 
the period corresponding with compression, in other 
words, that position in which all valves are closed. 



If no resistance be encountered, it is evident that the 
air or the gaseous mixture is escaping from the cylin- 
der by way of the admission-valve, the exhaust-valve, 
or the piston. The valves, ordinarily seated by springs, 
may remain open because their stems have become 
bound, or because some obstruction has dropped in 
between the disk and the seat. In a worn-out or badly 
kept engine the valves are likely to leak. If that be 
the case grinding is the only remedy. If a valve be 
clogged, which becomes sufficiently evident by manip- 
ulating the controlling levers, it is necessary simply to 
clean the stem and its guides in order to remove the 
caked oil which accumulates in time. If the engine be 
new, the binding of the valve-stems is often caused by 
insufficient play between the stems and their guides. 
Should this prove to be the case, the defect is remedied 
by rubbing the frictional surface of the stem with fine 
emery paper and by lubricating it with cylinder-oil. 
The exhaust-valve, however, should be lubricated only 
with petroleum. 

It is not unlikely that the exhaust-valve may leak 
for two other reasons. In the first place, the tension of 
the spring which serves to return the valve may have 
lessened and may be insufficient to prevent the valve 
from being unseated during suction. Again, the screw 
or roller serving as a contact between the lever and the 
valve-stem, may not have sufficient play, so that the 
lengthening of the stem on account of its expansion 
may prevent the valve from falling back on its seat. 
The first-mentioned defect is remedied by renewing 


the spring, or by the provision of an additional spring 
or of a counterweight in order to prevent the stoppage 
of the- motor. The second defect can be remedied by 
regulating the contact. 

Leakage past the piston may be caused bv the break- 
ing of one or more rings, by wear or binding of the 
rings, or by wear or binding of the cylinder. The 
whistling caused by the air or the mixture as it passes 
back proves the existence of this fault. 

Presence of Water in the Cylinder.— It may some- 
times happen that water may find its way into the cyl- 
inder with the gas by reason of the bad arrangement 
of the piping. It may also happen that water may 
enter the cylinder through the water-jacket joint. 
Again, the presence of water in the cylinder may be 
due to condensation of the steam formed bv the chem- 
ical union of the hydrogen of the gas and the oxygen of 
the air, which condensation is caused by the cool walls 
of the cylinder. The water may sometimes accumulate 
in the exhaust pipe and box, when they have been im- 
properly drained, and may thus return to the cylinder. 
Whatever may be its cause, however, the presence of 
water in the cylinder impedes the starting of the en- 
gine, because the gases resulting from the explosion are 
almost spontaneously chilled, thereby diminishing the 
working pressure. 

If electric ignition be employed, drops of water may 
be deposited between the contacts, thereby causing 
short circuits which prevent the passing of the spark. 

If there be no drain-cock on the cylinder, the diffi- 


J 37 


culty of starting the engine can be overcome only by 
ceaseless attempts to set it in motion. The leaky COB- 
dition of a joint as well as the presence of a particle of 
gravel in the cylinder-casting, through which the water 
can pass from the jacket, is attested by the bubbling up 
of gas in the water-tank at the opening of the supply 
tube. These bubbles are caused by the passage of the 
gas through the jacket after the explosion. If such 
bubbles be detected, the cylinder should be renewed 
or the defect remedied. In order to obviate any dan- 
ger, the stop-cocks of the water-jacket, which have 
already been described in a previous chapter, should be 
closed while the engine is idle. 

Imperfect Ignition. — The difficulties encountered in 
starting an engine, and caused by imperfect ignition, 
vary in their nature with the character of the igni- 
tion system employed, whether that system, for ex- 
ample, be of the electric, or of the incandescent or hot 
tube type. Frequently it happens that in starting an 
engine a hot tube may break. If the tube be of porce- 
lain the accident may usually be traced to improper 
fitting or to the presence of water in the cylinder. If 
the tube be of metal, its breaking is caused usually by 
a weakening of the metal through long use — an acci- 
dent that occurs more often in starting the engine than 
in normal operation, because the explosions at starting 
are more violent, owing to the tendency of the supply- 
pipes to admit an excess of gas at the beginning. 

A misfire arising from a faulty tube in starting may 
be caused by an obstruction or by leaks at the joints or 


in the body of the tube itself, thereby allowing a certain 
quantity of the mixture to escape before ignition, This 
defect in the tube is usually disclosed by a characteris- 
tic whistling sound. 

A tube may leak either at the bottom or at the top. 
In the first case, starting is very difficult, because the 
part of the mixture compressed toward the tube will 
escape through the opening before it reaches the in- 
candescent zone. In the second case, ignition may be 

Fig. 74. 
Ignition -iuIh^ provided 

-ith needle valves to facilitate starting. 

simply retarded to so marked an extent that a sufficient 
motive effect cannot be produced. An example of this 
retardation, artificially produced to facilitate the start- 
ing and to obviate premature explosions, is found in a 
system of ignition-tubes provided with a small cock 
or variable valve (Figs. 74 and 75). 

The mere enumeration of defects caused by leakage 
is sufficient to indicate the remedy to be adopted. It 
may be well to recall in this connection the important 
part played by the ignition-valve. If it be leaky, or if 



its free operation be impeded, starting will always be 

Electric Ignition by Battery or Magneto. — If the 
electric ignition apparatus, whatever may be the 
method by which the spark is produced, be imper- 
fect in operation, the first step to be taken is to ascertain 
whether the spark is produced at the proper time, in 
other words, slightly after the dead center in the par- 
ticular position given to the admission device at start- 
ing. If a coil and a battery be employed, it is advis- 
able to remove the plug and to place it with its arma- 
ture upon a well-polished metal surface to produce an 
electrical contact, preventing, however, the contact of 
the binding post with this metallic surface. The same 
method of inspection is adopted with the make-and- 
break apparatus of an electric magneto. In both cases 
it should be ascertained whether or not there is any 
short-circuiting. The contacts should be cleaned with 
a little benzine if thev are covered with oil or caked 

If no spark is produced at the plug or at the make- 
and-break device it may be inferred that the wires are 
broken or that the generating apparatus is out of order. 
A careful examination will indicate what measures are 
to be taken to cure the defects. 

Premature Ignition. —It has several times been 
stated that the moment of ignition of the gaseous mix- 
ture has a pronounced influence on the operation of 
gas-engines and upon their economy. 

Premature ignition takes place when there is a vio- 


lent shock at the moment when the piston leaps from 
the rear dead center to the end of the compression 
stroke. The violent effects produced are all the more 
harmful because they tend to overheat the interior of 
the engine and thereby to increase in intensity. 

Premature ignition may be due to several causes. 
If a valveless hot tube be employed it may happen 
that the incandescent zone is too near the base. If 
the tube be provided with a valve, it very frequently 
happens that the valve leaks or that it opens too soon. 
In the case of electric ignition, the circuit may be 
completed before the proper time, because of faulty 
regulation. The suggestions made in the preceding 
chapters indicate the method of remedying these 

Faulty ignition may have its origin not only in the 
method of ignition employed, but also in excessive heat- 
ing of the internal parts of the engine, caused by con- 
tinual overloading or by inadequate circulation of 

Passing to those cases of premature ignition of a 
special nature which are not due to any functional de- 
fect in the engine, but which are purely accidental in 
origin, such as the uncleanliness of the parts within the 
cylinder or the presence of some projecting part which 
becomes heated to incandescence during compression, 
it should first be stated that these ignitions, usually 
termed spontaneous, often occur well m advance of the 
end of the compression stroke, They are characterized 
by a more marked shock than that caused by ordin 



premature ignition and usually result in bringing the 
engine to a complete stop in a very short time. These 
spontaneous explosions counteract to such an extent 
the impulse of the compression period, during which 
the piston is moving back, that they have a tendency 
to reverse the direction in which the engine is running. 
In such cases a careful inspection and a scrupulous 
cleaning of the cylinder and of the piston should be 

The bottom of the piston is particularly likely to re- 
tain grease which has become caked, and which is 
likely to become heated to incandescence and sponta- 
neously to ignite the explosive mixture. 

Untimely Detonations. — The sound produced by 
the explosions of a normally operating engine can 
hardly be heard in the engine-room. Untimely detona- 
tions are produced either at the exhaust, or in the suc- 
tion apparatus, near the engine itself. These detona- 
tions are noisier than they are dangerous; still, they 
afford evidence of some fault in the operation which 
should be remedied. 

Detonations produced at the exhaust are caused by 
the burning of a charge of the explosive mixture in the 
exhaust-pipe, which charge, for some reason, has not 
been ignited in the cylinder, and has been driven into 
the exhaust-pipe, where it catches fire on coming into 
contact with the incandescent gases discharged from 
the cylinder after the following explosion. 

Detonations produced in the suction apparatus of 
the engine, which apparatus is either arranged in the 


base itself or in a separate chest, are often noisier than 
the foregoing. They are caused by the accidental back- 
ward flowing of the explosive mixture, and by its igni- 
tion outside of the cylinder. The accident may be 
traced to three causes: 

i. The suction-valve of the mixture may not be tight 
and may leak during the period of compression, allow- 
ing a certain quantity of the mixture to pass into the 
suction-chest or into the frame. When the explosion 
takes place in the cylinder that part of the mixture 
which has passed back is ignited, as we have just seen, 
thereby producing a very loud deflagration. The ob- 
vious remedy consists in making the suction-valve tight 
by carefully grinding it. 

2. It may happen that at the end of the exhaust 
stroke incandescent particles may remain in the cylin- 
der, which particles may consist of caked oil or may 
be retained by poorly cooled projections. The result is 
that the mixture is prematurely ignited during the suc- 
tion period. 

3. The engine is so regulated, particularly in the 
case of English-built engines, as to effect what is tech- 
nically called "scavenging" the products of combus- 
tion. In order to obtain this result, the mixture-valve 
is opened before the end of the exhaust stroke of the 
piston and the closing of the exhaust-valve. Owing to 
the inertia and the speed acquired by the products of 
combustion shot into the exhaust-pipe after explosion, 
a lowering of the pressure is produced in the cylinder 
toward the end of the stroke, causing the entrance of 



air by the open admission-valve and consequently 
effecting the scavenging of the burnt gases, part of 
which would otherwise remain in the cylinder. It is 
evident that if a charge of the mixture has not been 
normally exploded, either because its constituents have 
nut been mingled in the proper proportion, or hecause 
the ignition apparatus has missed fire, this charge at the 
moment of exhausting will pass out of the cylinder 
without any acquired speed, and will flow back in part 
at the end of the exhaust stroke past the prematurely 
opened admission-valve, therebv lodging in the air suc- 
tion apparatus. Despite the suction which takes place 
immediately following the re-entrance of the gas into 
the cylinder, a certain quantity of the mixture is still 
confined in the suction-pipe and its branches, where it 
will catch fire at the end of the exhaust stroke after the 
opening of the mixture-valve. 

In order to avoid these detonations it is necessary 
simply to see to it that the mixture is regularly ignited. 
This is accomplished by mixing the gas and air in 
proper proportions or by correcting the ignition time. 

Retarded Explosions.— Retarded explosions consid- 
erably reduce the power which an engine should nor- 
mally yield, and sensibly increase the consumption. 
They are due to three chief causes: (i), faulty igni- 
tion; (2), the poor quality of the mixture; {3), com- 
pression losses. The existence of the defect cannot be 
ascertained with any certainty without the use of an 
indicator or of some registering device which gives 
graphic records. Nevertheless, it is possible in some 


degree to detect retarded explosions, simply by ob- 
serving whether there is a diminution in the power or 
an excessive consumption, despite the perfect operation 
and good condition of all the engine parts. 

In order to remedy the defect it should be ascer- 
tained if the compression is good, if the supply of gas 
is normal, and if the conditions under which the mix- 
ture of air and gas is produced have not heen changed. 
Lastly, the ignition apparatus is gradually adjusted to 
accelerate its operation until a point is reached when, 
after explosion, shocks are produced which indicate an 
excessive advance. The ignition apparatus is then ad- 
justed to a point slightly ahead of the corresponding 
position. Recalling the descriptions already given of 
the various systems of ignition, the manner of regulat- 
ing the moment of ignition in each case may be sum- 
marized as follows: 

i. For the valveless incandescent tube, provided 
with a burner the position of which can be varied, 
ignition can be accelerated by bringing the burner 
nearer to the base. Retardation is effected by moving 
the burner away from the base. 

2, In the case of the incandescent tube of the fixed 
burner type, the moment of ignition will depend upon 
the length of the tube. The retardation will be greater 
as the tube is shorter, and vice versa. 

3. If the tube be provided with an ignition-valve, 
the time of ignition having been regulated by the 
maker, regulation need not be undertaken except if the 
valve-stem be worn or the controlling-cam be distorted. 



If these defects should be noted, the imperfect parts 
should be repaired or renewed. 

4. In electric igniters the controlling apparatus 
is generally provided with a regulating device which 
may be manipulated during the operation of the motor, 
If the manual adjustment of the regulating apparatus 
be unproductive of satisfactory results, it is advisable 
to ascertain whether the spark is being produced nor- 
mally. Before the engine has come to a stop, one of 
the valve-casings is raised, and through the opening 
thus produced it is easily seen whether the spark is of 
sufficient strength, the engine in the meanwhile being 
turned by hand. Care should always be taken to purge 
the cylinder of the gas that it may contain, in order to 
prevent dangerous explosions. If the spark should 
prove to be too feeble, or if there be no spark at all, de- 
spite the fact that every part of the mechanism is prop- 
erly adjusted, it may be inferred that the fault lies with 
the current and is caused by 

1. Imperfect contact with the binding-posts, with 
the conducting wire, or with the contact-breaking 

2. A short circuit in one of the dismembered pieces ; 

3. The presence of a layer of oil or of caked grease 
forming an insulator, injurious to induction, between 
the armature and the magnets; 

4. A deposit of oil or moisture on the contact-break- 
ing parts; 

5. The exhaustion of the magnets, which, however, 
occurs only after several years of use, except when the 


magneto has been subjected for a long time to a high 

The mere discovery of any of these defects suffi- 
ciently indicates the means to be adopted in remedying 

Lost Motion in Moving Parts. — Lost motion of 
the moving parts is due to structural errors. Its cause 
is to be found in the insufficient size of the frictional 
bearing surfaces, and improper proportioning of shafts, 
pins, and the like. The result is a premature wear 
which cannot be remedied. Imperfect adjustment, 
lack of care, and bad lubrication, may also hasten the 
wear of certain parts. This wear is manifested in 
shocks, occurring during the operation of the engine, — 
shocks which are particularly noticeable at the moment 
of explosion. 

Besides the inconveniences mentioned, wearing of the 
gears and of the moving parts leads to derangement of 
the power-transmitting members. 

So far as the admission and exhaust valves are con- 
cerned, the wearing of the cams, rollers, and lever- 
pivots is evidenced by a retardation in the opening of 
these valves and an acceleration in their closing. 

The ignition, whatever may be the system employed, 
is affected by lost motion and is retarded. The engine 
appreciably loses in power, and its consumption be- 
comes excessive. 

Overheated Bearings.— Apart from the imperfect 
adjustment of a member, it may happen that the bush- 
ings of the main bearings of the ends of the connecting- 



rod, and of the piston-pivot, may become heated be- 
cause of excessive play, or of too much tightening, or of 
a lack of oil, or of the employment of oil of bad quality. 
The overheating may lead to the binding of frictional 
surfaces and even to the fusion of bushings if they be 
lined with anti-friction metal. In order to avoid the 
overheating of parts, it is advisable, while the engine 
is running, to touch them from time to time with the 
back of the hand. As soon as the slightest overheating 
is felt, the temperature may be lowered often by liberal 
oiling. If this be inadequate and if for special reasons 
it is impossible to stop the engine, the overheated part 
may be cooled bv spraying it with soapy water. 

If the overheating has not been detected or reduced 
in time, a characteristic odor of burnt oil will be per- 
ceived, accompanied by smoke. The part overheated 
will then have attained a temperature so high that it 
cannot be touched with the hand. Should this occur, 
it is inadvisable to employ oil, because it would im- 

diatcly burn up and would only aggravate the con- 
ditions. Cotton waste should be carefully applied to 
overheated member, and gradual spraying with 

apy water begun. 

In special cases where the lubricating openings or 

annels are not likely to be obstructed, a little flowers 

sulphur may be added to the oil, if this be very fluid. 
Castor oil may also be successfully employed. 

If the binding of the rubbing surfaces should pre- 
vent the reduction of the overheated member's tempera- 
ture, the engine must necessarily be stopped, and the 


l 4 B 

parts affected detached. All causes of binding are re- 
moved by means of a steel scraper. The surfaces of the 
bushings and of the shaft which they receive are 
smoothed with a soft file and then polished with fine 
emery paper. Before the parts are replaced, the pre- 
caution of ascertaining whether they touch at all points 
should be taken. Careful inspection and copious lubri- 
cation should, of course, be undertaken when the en- 
gine is again started. 

Overheating of the Cylinder.— The overheating of 
the cylinder may be due to a complete lack of water 
in the jacket or to an accidental diminution in the quan- 
tity of water supplied. If this discovery is made too 
late, and if the cylinder has reached a very high tem- 
perature, the circulation of the water should not be 
suddenly re-established, because of the liability of 
breaking the casting. It is best to stop the engine and 
to restore the parts to their normal condition. 

It is well to recall at this point that if the calcareous 
incrustation of the water-jacket or the branch pipes 
should hinder the free circulation of water, cleaning is, 
of course, necessary. The jacket may be washed sev- 
eral times with a twenty per cent, solution of hydro- 
chloric acid. After this treatment the jacket should, of 
course, be rinsed with fresh water before the piping of 
the water-circulating apparatus is again connected. 

Overheating of the Piston.— If the overheating of 
the piston is not due to faulty adjustment, it may be 
caused by lack of oil or to the employment of a lubri- 
cant not suitable for the purpose. In a previous chap- 



ter the importance of using a special oil for cylinder 
lubrication has been insisted upon. The overheating 
of the piston can also result from that of the piston-pin. 
Should this be the case it is advisable to stop the engine, 
to ascertain the condition and the degree of lubrica- 
tion of this member and its bearing. Overheating of 
the piston is manifested by an increase of the tempera- 
ture of the cylinder at the forward end. If this over- 
heating be not checked, binding of the piston in the 
cylinder is likely to result. 

Smoke Arising from the Cylinder.— This is gen- 
erally a sign either of overheating, which causes the 
oil to evaporate, or of an abnormal passage of gas, 
caused by the explosion. Abnormal passage of gas 
may result from wear or from distortion of the cylin- 
der, or from wear or breakage of the piston-rings. The 
result is always the overheating of the cylinder and a 
reduction in compression and power. 

If the engine is well kept and shows no sign of wear, 
leakage may be caused simply by the fouling of the 
piston-rings, which then adhere in their grooves and 
have but insufficient play. This defect is obviated by 
cleaning the rings in the manner explained in Chapter 

Lubrication is faulty when the quantity of lubricant 
supplied is either insufficient or too abundant, or when 
the oils employed are of bad quality. It has already 
been shown that insufficient lubrication and the utiliza- 
tion of bad oils leads to the overheating of the moving 


Insufficient lubrication may be caused by imperfect 
operation of the lubricators, or, particularly during 
cold weather, by too great a viscosity or congelation of 
the oil. If a lubricator be imperfect in its operation, 
the condition of its regulating mechanism should be as- 
certained, if it has any, and an examination made to dis- 
cover any obstruction in the oil-ducts. Such obstruc- 
tions are very likely to occur in new devices which have 
been packed in cotton waste or excelsior, with the re- 
sult that the particles of the packing material often find 
their way into openings. 

An oil may be bad in quality because of its very 
nature, or because of the presence of foreign bodies. 
In either case an oil of better quality should be sub- 

The freezing of oil by intense cold may be retarded 
bv the addition of ordinary petroleum to the amount of 
10 to 20 per cent. 

An excess of oil in the bearings results simply in 
an unnecessary waste of lubricant, and the splashing 
of oil on the engine and about the room. If too much 
oil be used in the cylinder, grave consequences may be 
the result; for a certain quantity of the oil is likely to 
accumulate within the cylinder, where it burns and 
forms a caky mass that may be heated to incandescence 
and prematurely ignite the explosive mixture. Es- 
pecially in producer-gas engines is an excess of cylin- 
der-lubricant likely to cause such accidents. Indeed, 
the temperature of explosion not being as high as in 
street-gas engines, the excess oil cannot be so readily 


removed with certainty by evaporation or combustion. 
On the other hand, the compression of the mi\tuic 
being generally higher, premature ignition is vei\ 
likely to occur. 

Back Pressure to the Exhaust. — Mow the pipes ami 
chests for the exhaust should be arranged in ordet not 
to exert a harmful influence on the motor has aliead\ 
been explained. Even if the directions given have been 
followed, however, the exhaust may not operate prop 
erly from accidental causes. Among these causes may 
be mentioned obstructions in the form of foreign bod 
ies, such as particles of rust, which drop from the in 
terior of the pipes after the engine has been running 
for some time and which, accumulating at any place in 
the pipe, are likely to clog the passage. Furthermore, 
the products of combustion may contain atomized cyl- 
inder oil which finds its way into the exhaust-pipe. 
This oil condenses on the walls of the elbows and bends 
of the pipe in a deposit which, as it carbonizes, is con- 
verted into a hard cake and which reduces the cross- 
section of the passage, thereby constituting a true ob- 
stacle to the free exhaust of the gases. 

These various defects are manifested in a loss in 
engine power as well as in an abnormal elevation of 
the temperature of the parts surrounding the exhaust 

Sudden Stops. — Sudden stops are occasioned by 
faulty operation of the engine, and by imperfect fuel 
supply. Among the first class the chief causes to be 
mentioned are the following: 


1. Overheating, which has already been discussed 
and which may block a moving part. 

2. Defective ignition. 

3. Binding of the admission-valve or of the exhaust- 
valve, preventing respectively suction or compression. 

4. The breaking or derangement of a member of the 
distributing mechanism. 

5. A weakening of the exhaust-valve spring, so that 
the valve is opened by the suction of fresh quantities of 

These faults are due to carelessness and improper in- 
spection of the engine. 

So far as the fuel supply of the engine is concerned, 
the causes of stoppage will vary if street-gas or pro- 
ducer-gas be employed. In the former case the diffi- 
culty may be occasioned by the improper operation of 
the meter, by the formation of a water-pocket in the 
piping, by the binding of an anti-pulsator valve, by the 
derangement of a pressure-regulator, or by a sudden 
change in the gas pressure when no pressure-regulator 
is employed. If producer-gas be used, stoppages may 
be occasioned by a sudden change in the quality, quan- 
tity, or temperature of the gas. These defects will be 
examined in detail in the chapter on Gas-Producers. 



Thus far only street-gas or illuminating-gas engines 
have been discussed. If the engine employed be small 
— 10 to 15 horse-power, for instance — street-gas is a 
fuel, the richness, purity and facility of employment 
of which offsets its comparatively high cost. But 
the constantly increasing necessity of generating 
power cheaply has led to the employment of special 
gases which are easily and cheaply generated. Such 
are the following: 

Blast-furnace gases, 

Coke-oven gases, 

Fuel-gas proper, 

Mond gas, 

Mixed gas, 



The practical advantages resulting from the utiliza- 
tion of these gases in generating power were hardly 
known until within the last few years. The many uses 
to which these gases have been applied in Europe since 
1900 have definitely proved the industrial value of pro- 
ducer-gas engines in general. 

The steps which have led to this gradually increasing 
use of producer-gas have been learnedly discussed and 
commented upon in the instructive works and publica- 


tions of Aime Witz, Professor in the Faculty of 
Sciences of Lille, in those of Dugald Clerk, of Lon- 
don, F. Graver, of Leeds, and Otto Guldner, of Mu- 
nich, and in those of the American authors, Golding- 
ham, Hiscox, Hutton, Parsell and Weed, etc. The 
new tendencies in the construction of large engines may 
be regarded as an interesting verification of the fore- 
casts of these men — forecasts which coincide with the 
opinion long held bv the author. Aime Witz has 
always been an advocate of high pressures and of in- 
creased piston speed. English builders who made ex- 
periments in this direction conceded the beneficial re- 
sults obtained; but while they increased the original 
pressure of 28 to 43 pounds per square inch employed 
five or six years ago to the pressure of 85 to 100 pounds 
per square inch nowadays advocated, the Germans, for 
the most part, have adopted, at least in producer-gas 
engines, pressures of 114 to 170 pounds per square 
inch and more. 

High Compression. — In actual practice, the problem 
of high pressures is apparently very difficult of solu- 
tion, and many of the best firms still seem to cling to 
old ideas. The reason for their course is, perhaps, to 
be found in the fact that certain experiments which they 
made in raising the pressures resulted in discouraging 
accidents. The explosion-chambers became over- 
heated; valves were distorted; and premature ignition 
occurred. Because the principle underlying high pres- 
sures wits improperly applied, the results obtained were 



High pressures cannot be used with impunity in cyl- 
inders not especially designed for their employment; 
and this is the case with most engines of the older type, 
among which may be included most engines of English, 
French, and particularly of American construction. 
In American engines notably, the explosion-chamber, 
the cylinder and its jacket, are generally cast in one 
piece, so that it is very difficult to allow for the free ex- 
pansion of certain members with the high and unequal 
temperatures to which they are subjected (Fig. 22). 

Some builders have attempted to use high pressures 
without concerning themselves in the least with a modi- 
fication of the explosive mixture. The result has been 
that, owing to the richness of the mixture, the explosive 
pressure was increased to a point far beyond that for 
which the parts were designed. Sudden starts and stops 
in operation, overheating of the parts, and even break- 
ing of crank-shafts, were the results. The engines had 
gained somewhat in power, but no progress had been 
made in economy of consumption, although this was 
the very purpose of increasing the compression. 

High pressures render it possible to employ poor 
mixtures and still insure ignition. A quality of street- 
gas, for example, which vields one horse-power per 
hour with 17.5 cubic feet and a mixture of 1 part gas 
and 8 of air compressed to 78 pounds per square inch, 
will give the same power as 14 cubic feet of the same 
gas mixed with \2 parts of air and compressed to iji 
pounds per square inch. 

" Scavenging " of the cylinder, a practice which en- 


gineers of modern ideas seem to consider of much im- 
portance, is better effected with high pressures, for the 
simple reason that the explosion-chamber, at the end 
of the return stroke, contains considerably less burnt 
gases when its volume is smaller in proportion to that 
of the cylinder. 

In impoverishing the mixture to meet the needs of 
high pressures, the explosive power is not increased and 
in practice hardly exceeds 365 10427 pounds per square 


Fig. 76. — Method of cooling [he cylinder-head, 

inch. With the higher pressures thus obtained there 
is consequently no reason for subjecting the moving 
parts to greater forces. 

Cooling, — The increase in temperature of the cylin- 
der-head and of the valves, due wholly to high com- 
pression, is perfectly counteracted by an arrangement 
which most designers seem to prefer, and which, as 
shown in the accompanying diagram (Fig. 76) , con- 
sists in placing the mixture and exhaust-valves in a 
passage forming a kind of antechamber completely 



surrounded by water. The immediate vicinity of this 
water assures the perfect and equal cooling of the valve- 
seats. This arrangement, while it renders it possible to 
reduce the size of the explosion-chamber to a mini- 
mum, has the additional mechanical advantage of en- 
abling the builder to bore the seats and valve-guides 
with the same tool, since they are all mounted on the 
same line. From the standpoint of efficiency, the de- 
sign has the advantage of permitting the introduction 
of the explosive mixture without overheating it as it 
passes through the admission-valve, which obtains all 
the benefit of the cooling of the cylinder-head, literally 
surrounded as it is by water. 

In large engines the cooling effect is even heightened 
by separately supplying the jackets of the cylinder- 
head and of the cylinder. In engines of less power the 
top of the cylinder-head jacket is placed in communica- 
tion with that of the cylinder, so that the coldest water 
enters at the base of the head and, after having there 
been heated, passes around the cylinder in order finally 
to emerge at the top toward the center. The water hav- 
ing been thus methodically circulated, the useful effect 
and regularity of the cooling process is increased. 

Notwithstanding the care which is devoted to water 
circulation, it is advisable to run the producer-gas en- 
gine " colder " than the older street-gas types, in which 
the more economic speed is that at which the water 
emerges from the jacket at about a temperature of 104 
degrees F. It would seem advisable to meet the re- 
quirements of piston lubrication by reducing to a mini- 



mum the quantity of heat withdrawn by the circulating 
water. Indeed, the personal experiments of the author 
bear out this principle. 

For street-gas engines, however, the cylinders should 
be worked at the highest possible temperature consistent 
with the requirements of lubrication. It should not be 
forgotten that, in large engines fed with producer-gas, 
economy of consumption is a secondary consideration, 
because of the low quantity of fuel required. The cost, 
moreover, may well be sacrificed to that steadiness of 
operation which is of such great importance in large en- 
gines furnishing the power of factories; for in such 
engines sudden stops seriously affect the work to be 
performed. For this reason engine builders have been 
led to the construction of motors provided with very 
effective cooling apparatus. Since the circulation 
of the water around the explosion-chamber and the 
cylinder is not sufficient to counteract the rise of tem- 
perature, it has become the practice to cool separately 
each part likely to be subjected to heat. The seats of 
the exhaust-valves, the valves themselves, the piston, 
and sometimes the piston-rod, have been provided with 

Premature Ignition. — Returning to the causes of the 
discouragements encountered by some designers who 
endeavored to use high pressures, it has already been 
mentioned that premature ignition of the explosive 
mixture in cylinders not suited for high pressures is one 
reason for the bad results obtained. An explanation of 
these results is to be found in the high theoretical tern- 


perature corresponding with great pressures and in the 
quantity of heat which must be absorbed by the walls 
of the explosion-chamber. These two circumstances 
are in themselves sufficient to produce spontaneous igni- 
tion of excessively rich mixtures, compressed in an over- 
heated chamber unprovided with a sufficient circulation 
of water. A third cause of premature ignition may also 
be found in the old system of ignition which, in most 
English engines, consists of a metallic or porcelain tube, 
the interior of which communicates with the explosion' 
chamber, an exterior flame being employed to best the 
tube to incandescence. In tubes of this type which are 
not provided with a special ignition-valve, the time of 
ignition is dependent only on the moment when the ex- 
plosive mixture, driven into the tube, comes into con- 
tact, at the end of the compression stroke, with the in- 
candescent zone, thereby causing the ignition. This 
very empirical method leads either to an acceleration 
or retardation of the ignition, depending upon the 
temperature of the tube, the position of the red-hot zone, 
its dimensions, and the temperature of the mixture, 
which is determined by the load of the engine. Al- 
though this system, the only merit of which is its sim- 
plicity, may meet the requirements of small engines, 
there is not the slightest doubt that it is quite inapplica- 
ble to those of more than 20 to 25 horse-power, for 
in such engines greater certainty in operation is de- 
manded. Even if only the more improved of the two 
types of hot-tube ignition be considered, with or with- 
out valves, it must still be held that they are inapplica- 


ble to high compression engines. The ignition-valve 
is the part which suffers most from the high tem- 
perature to which it is subjected. Its immediate 
proximity to the incandescent tube, and its contact 
with the burning gas when it flares up, render 
it almost impossible to employ any cooling arrange- 
ment. Although with the exercise of great care it may 
work satisfactorily in engines of normal pressure, it is 
evident that it cannot meet the requirements of high- 
pressure engines, because the temperature of the com- 
pressed mixture is such that the charge is certain to 
catch fire by mere contact with the overheated valve. 
In industrial engines of small size, premature ignition 
has little, if any, effect except upon silent operation and 
economic consumption. This does not hold true, how- 
ever, of large engines. Besides the inconveniences men- 
tioned, there is also the danger of breaking the cranks 
or other moving parts. The inertia of these members is 
a matter of some concern, because of their weight and 
of the linear speed which they attain in large engines. 
Some idea of this may be obtained when it is considered 
that in a producer-gas or blj$t-furnace-gas engine hav- 
ing a piston diameter of 24 inches and an explosive 
pressure of 299 pounds per square inch, the force ex- 
erted at the moment of explosion is about 132,000 
pounds. Naturally, engine builders have adopted the 
most certain means of avoiding premature ignition and 
its grave consequences. 

The method of ignition which at present seems to be 
preferred to any other for producer-gas is that employ- 



ing a break-spark obtained with the magneto apparatus 
previously described. Some builders of large engines, 
particularly desirous of assuring steadiness of running, 
have provided the explosion-chamber with two inde- 
pendent igniters. It may be that they have adopted 
this arrangement largely for the purpose of avoiding 
the inconveniences resulting from a failure of one of the 
igniters, rather than for the purpose of igniting the 
mixture in several places so as to obtain a more uniform 
ignition and one better suited for the propagation of 
the flame. 

The Governing of Engines.— Various methods have 
been adopted for the purpose of varying the mo- 
tive power of an engine between no load and full load, 
still preserving, however, a constant speed of rotation. 
These methods consist in changing either the quantity 
or the quality of the mixture admitted into the cylinder. 
Thus it may happen that an engine may be supplied: 

r. With a mixture constant in quality and in quan- 

2. With a mixture variable in quality and constant 
in quantity; 

3. With a mixture constant in quality and variable 
in quantity. 

1. Mixture Constant in Quality and Quantity. — This 
method implies the use of the hit-and-miss system of 
admission, in which the number of admissions and ex- 
plosions varies, while the value or the composition of 
each admitted charge remains as constant as the com- 
pression itself (Fig. 34). This system has already been 


referred to and its simplicity fully set forth. By its 
use a comparatively low consumption is obtained, even 
when the engine is not running at full load. On the 
other hand, it has the disadvantage of necessitating the 
employment of heavy, fly-wheel to preserve cyclic reg- 

2. Mixture Variable in Quality and Constant in 
Quantity— -The governing system most commonly em- 
ployed to obtain a mixture variable in quality and con- 
stant quantity is based upon the control of the gas- 
admission valve by means of a cam having a conical 
longitudinal section, as shown in Fig. 35. This cam, 
commonly called a " conical cam, 1 ' is connected with a 
lever actuated from the governor. As the lever swings 
under the action of the governor, the cam is shifted 
along the half-speed shaft of the engine. The result is 
that the gas-admission valve is opened for a longer or 
shorter period. 

In another system a cylindrical valve is mounted 
between the chamber in whichthe mixture is formed 
and the gas-supply pipe, the valve being carried on the 
same stem as the mixture-valve itself. The cylindrical 
valve is displaced by the governor so as to vary the 
quantity of gas drawn in with relation to the quantity 
of air. 

When the engines are fed with producer-gas the 
parts which have just been described should be fre- 
quently inspected and cleaned; for they are only too 
easily fouled. 

Engines thus governed should be run at high pres- 


sure so as to insure the ignition of the producer-gas 
mixtures formed when the position of the cam cor- 
responds with the minimum opening of the gas-valve. 
Powerful governors should be employed, capable of 
overcoming the resistance offered by the cylindrical 
valve or the cam. 

It may often happen that variations in the load of the 
engine render it necessary to actuate the air valve, so 
as to obtain a mixture which will be ignited and ex- 
ploded under the best possible conditions. 

3. Mixture Constant in Quality and Variable in 
Quantity. — In supplying an engine with a mixture con- 
stant in quality and variable in quantity, the compres- 
sion does not remain constant. The quantity of mixture 
drawn in by the cylinder may even be so far reduced 
that the pressure drops below the point at which igni- 
tion takes place. For that reason engines of this type 
should be run at high pressures. 

The variation of the quantity of mixture may be 
effected in various ways. The simplest arrangement 
consists in mounting a butterfly-valve in the mixture- 
pipe, which valve is controlled by the governor and 
throttles the passage to a greater or lesser degree. 
A very striking solution of the problem consists in vary- 
ing the opening of the mixture-valve itself. To attain 
this end the valve is moved by levers. The point of 
application of one of these levers is displaced under 
the action of the governor so as to vary the travel of 
the valve within predetermined limits. Under these 
conditions a mixture of constant homogeneity is intro- 



duced into the cylinder, so proportioned as to insure 
ignition even at low pressures. 

In recent experiments conducted by the author it was 
proved that with this governing system ignition still 
takes place even though the pressure has dropped to 

Fig. 76a. — Governing 

for producer-gas engine 

43 pounds per square inch. This system has the merit 
of rendering it possible to employ ordinary governors 
of moderate size, since the resistance to be overcome 
at the point of application of the lever is comparatively 
small. In the accompanying illustration the Otto 
Deutz system is illustrated. 



It may here be not amiss to point out the differences 
between illuminating gas and those gases which are 
called in English " producer " gases, and in French 
" poor " gases, because of their low calorific value. 

Street -Gas. — This gas, the composition of w r hich 
varies with different localities, has a calorific value, 
which is a function of its composition, and which varies 
f:om 5,000 to 5,600 calories per cubic meter (19,841 to 
24,896 B. T. U. per 35.31 cubic feet) measured at con- 
stant pressure and corrected to o degrees C. (32 degrees 
F.) at a pressure of 760 millimeters (29.9 inches of 
mercury, or atmospheric pressure), not including the 
latent heat of the water of condensation. The follow- 
ing table gives the average volumetric composition pf 
illuminating gas in various cities: 


Carbon monoxide. . . 


Various hydrocarbons 

Carbon dioxide 


















9 ' 











• • 



• • 








• • 


• • 

• • 








Furthermore, these constituents vary within certain 
limits. This is also true of the calorific value. Experi- 
ments made by the author have demonstrated that in 
the same place at an interval of a few hours, variations 
of approximately ten per cent, occur. 

Composition of Producer-Gases. — The average 
chemical composition of producer-gases varies with the 
conditions under which they are generated and the na- 
ture of the fuel. The following are the proportions of 
its constituents expressed volumetrically: 




r^« t . 


Miitd W'jkt 


Nitrogen and oxygen 






■ 6 






1 1 


_ Q 







Calorific value in calories. 
AwBge weight of a cubic 

meter in kilos 

Or of a cubic foot in 



1,1 00 

I .OS 

l,o S 





Blast-furnace gas has been used for generating power 
by means of gas-engines for about ten years. At the 
present time it is used in engines of very high power, 
a discussion of which engines more properly belongs 
to a work, on metallurgy, and has no place, therefore, 
in a manual such as this. 

Producer-gas, in the true sense of the term, is gen- 
erated in special apparatus either under pressure or by 



suction in a manner to be described in the following 

Mond gas is produced in generators of the blowing 
or pressure type from bituminous coal, necessitating the 
employment of special purifiers and permitting the col- 
lection of the by-products of the fractional distillation 
of the coal. Mond gas plants are, therefore, rather 
complicated and can be advantageously utilized only 
for large engines. More exhaustive information can 
be obtained from the descriptions published by the 
builders of Mond gas generators. 

Mixed gas is generated in apparatus arranged so that 
the retort is kept at a high temperature, thereby produc- 
ing a gas richer in hydrogen than that made by pro- 
ducers. It should be observed that in practice the gen- 
erators at present used yield a producer-gas, the calo- 
rific value of which fluctuates between 1,000 and 1,400 
calories per cubic meter (3,968 to 5,158 B. T. U. per 
35.31 cubic feet) ; and the composition varies accord- 
ingly, in the manner that has already been indicated 
in the tables for producer-gas and mixed gas. There 
is no necessity, therefore, for drawing a distinction be- 
tween these two qualities of gas. 

Water-gas should theoretically be composed of 50 
per cent, carbon monoxide and 50 per cent, hydrogen, 
resulting from the decomposition of steam by in- 
candescent coal. In practice, however, it contains a 
little nitrogen and carbon dioxide. The gas is obtained 
from generators in which air is alternately blown in to 
fan the fire and then steam to produce gas. Water-gas 

1 68 


is employed in soldering on account of its reducing 
properties and of the high temperature of its flame. 
The great quantity of carbon monoxide which it con- 
tains renders it very poisonous and exceedingly danger- 
ous, because it is generated under pressure. From the 
economical standpoint, its generation is more expen- 
sive than that of producer-gas, for which reason its 
emplovment in gas-engine's is hardly of much value. 

Wood-gas, the composition of which has already been 
given, is generated in apparatus of the Riche type, the 
principle of which consists in heating a cast retort 
charged with any kind of fuel, namely wood, and ver- 
tically mounted on a masonry base. 

This apparatus should be of .particular interest to 
the proprietors of sawmills, furniture factories, and the 
like, since it offers a means of using the waste products 
of their plants. 

The relatively high proportion of carbon monoxide 
in producer-gas is objectionable from a hygienic stand- 
point, so much so, indeed, that it has attracted the atten- 
tion of manufacturers. Carbon monoxide, the specific 
gravity of which is 0.967, is a gas peculiarly poisonous 
and dangerous. It cannot be breathed without baneful 
effects, and is even more dangerous than carbonic-acid 
gas, which eventually causes asphyxiation by reducing 
the quantity of oxygen in the air. For this reason, it is 
necessary to take the utmost precaution in efficiently and 
continuously ventilating the rooms in which the gas- 
generators and their accessories are installed. This 
suggestion should be followed, above all, when the ap- 


paratus in question are installed in cellars and base- 
ments. As a further precaution, where the plant is 
rather large a workman should not be allowed to enter 
the generator room alone. 

Blowing-generators, or those in which the gas is pro- 
duced under pressure, are more dangerous than suc- 
tion-generators. In the former a leaky joint may cause 
the vitiation of the surrounding air as the producer-gas 
escapes; in the suction apparatus the same fault simply 
causes more air to be drawn in. 

Dr. Melotte recommends the following procedure 
in cases of carbon monoxide asphyxiation: 

Carbon Monoxide Asphyxiation 

Cases of poisoning by carbon monoxide are both fre- 
quent and dangerous. The gas is extremely poisonous, 
and all the more dangerous because it is odorless, color- 
less and tasteless. When it comes into contact with the 
blood, it forms a combination so stable that it is reacted 
upon by the oxygen of the air only with difficulty. It 
follows, therefore, that with each respiration of air 
charged with carbon monoxide, a certain quantity of 
blood is poisoned. In consequence of this, there is a 
possibility of poisoning in open air. 

Symptoms. — The symptoms observed will vary with 
the manner in which the blood has been poisoned. 
There are two ways in which this poisoning can occur. 
The one depends upon whether the atmosphere contains 
an excess of carbon monoxide; the other whether the 
air breathed contains only traces of the gas. 




Gradual, Rapid Asphyxiation.— At first a vague 

sickness is felt, rapidly followed by violent headaches, 
vertigo, anxiety, oppression, dimness of vision, beating 
of the pulse at the temples, hallucinations, and an irre- 
sistible desire to sleep. If at this stage the patient has a 
sufficient idea of danger to prompt him to open a 
window or door, he will escape death. 

In the second stage, the victim's legs are paralyzed, 
but he can still move his arms and his head. The mind 
still preserves its clearness, and in a measure assists the 
further process of asphyxiation because of its impo- 
tency. Then follow coma and death. 

Slow, Chronic Asphyxiation.— Slow, chronic as- 
phyxiation is not infrequent. Its symptoms are often 
difficult to detect. Poisoning is manifested by weak- 
ness, cephalalgia, vomiting, pallor, general anemia, las- 
situde, and local paralysis. If any of these symptoms 
appear in the men who work in the vicinity of the pro- 
ducers, immediate steps should be taken to prevent the 
possibility of carbon monoxide asphyxiation. 

First Aid in Cases of Carbon Monoxide Poisoning 

It has already been stated that the oxvgen of the air 
has no oxidizing effect upon blood contaminated by 
carbon monoxide. Only a liberal current of pure 
oxygen can oxidize the combination formed and render 
hematosis possible. This liberal current can be ob- 
tained from an oxygen tank of the portable variety, pro- 
vided with a tube carrying at its free end a mask which 


is held over the mouth and the nostrils. The absorption 
of gas takes place by artificial respiration, which is 
effected in several ways. The most practical of these 
are the Sylvester and Pacini methods. 

Sylvester Method. — The patient is laid on his back. 
His arms are raised over his head and then brought 
back on each side of the body. This operation is re- 
peated fifteen times per minute approximately. The 
method is very frequently employed and is excellent in 
its results. 

The Pacini Method. —Four fingers are placed in 
the pit of the arm, with the thumb on the shoulder. 
The shoulder is then alternately raised and lowered, 
producing a marked expansion of the chest. This 
method is the more effective of the two. The move- 
ments described are repeated fifteen to twenty times 
each mini'te very rhythmically. 

One or the other of these two methods of treatment 
should be immediately applied in serious cases. Cer- 
tain preliminary precautions should be taken in all 
cases, however. The patient should be carried to a well- 
ventilated and moderately heated room, stripped of his 
clothes, and warmed by water-bottles and heated linen. 
Reflex action should be excited, the peripheral nervous 
system stimulated in order to contract the heart and the 
respiratory muscles, and the precordial region cauter- 
ized. In addition to this treatment, the region of the dia- 
phragm should be rubbed and pinched, the skin rubbed, 
cold showers given, flagellations administered, urtica- 
tions (whipping with nettles) undertaken, the skin and 


the mucous membranes excited, the mucous membrane 
of the nose and of the pharynx titillated with a feather 
dipped in ammonia, alcohol, vinegar, or lemon juice. 

Rhythmic traction of the tongue is effective when car- 
ried out as follows: The tongue is seized with a forceps 
and kept extended by means of a coarse thread. It is 
then pulled out from the mouth sharply and allowed to 
reenter after each traction. These movements should 
be rhythmic and should be repeated fifteen to twenty- 
times a minute. 

All these efforts should be continued for several 
hours. When the patient has finally been revived, he 
should be placed in a warm bed. Stimulants such as 
wine, coffee, and the like should be administered. If 
the head should be congested, local blood-letting should 
be resorted to and four or six leeches applied behind 
the ears. It should be borne in mind that the various 
steps enumerated are to be taken pending the arrival 
of a physician. 

Imparities of the Gases 

Most of the coal used in generating producer-gas 
contains sulphur. Sulphuretted hydrogen is thus pro- 
duced, which mixes with the gas and imparts to it its 
characteristic odor. In some gas-generators, purifiers 
are employed in which sawdust mixed with iron salts 
is utilized, with the result that a combination is formed 
with the sulphuretted hydrogen, thereby removing it 
from the producer-gas. In other forms of generators 


a more summary method of purification is adopted, so 
that traces of sulphuretted hydrogen still remain. 
Since this gas attacks copper, the employment of this 
metal is not advisable for the following apparatus: 
Generator (openings,, cock for testing the gas) ; piping 
(gas-pressure cocks, drain and pet cocks) ; engine (gas- 
admission cock, lubricating joint in the cylinder, valves 
and cocks of the compressed-air starting-pipe). 

The distillation of coal in generators results in the 
formation of ammonia gas. This also has a corrosive 
action on copper and its alloys; but owing to its great 
solubility, it is eliminated by the waters of the " scrub- 
ber " and does not reach the engine. 

Production and Consumption 

The quantity of gas produced in most generators 
varies from 6.4 to 8.2 pounds per cubic foot of raw coal 
burnt in the generator. The engine consumes per 
horse-power per hour 70 to 115 cubic feet of gas, de- 
pending upon its richness. 



AS we have already seen, producer-gas as a fuel for 
engines may be generated in two kinds of apparatus, the 
one operating under pressure, and the other by suction. 

Dowson Gas-Producers. — The first pressure-gen- 
erators were introduced bv Dowson of London and 
necessitated installations of quite a complicated nature. 
Later improvements made by the designers contrib- 
uted much to the general employment of their system. 
Many installations varying from 50 to 100 horse- 
power and more may be found in the United Kingdom, 
all of them made by Dowson. Indeed, for a long time 
the name of Dowson was coupled, with producer-gas 
itself. The Dowson system necessitates the utilization 
of anthracite or of comparatively hard coal, such as 
that mined in Wales and Pennsylvania. Owing to the 
necessity of employing this special quality of coat the 
Dowson system and the systems that sprang from it 
were burdened with cooling, washing, and purifying 
apparatus, which complicated the installations to such 
an extent that they resembled gas works. The genera- 
tor that took the place of the retort was fed with air 
and steam, blown in under pressure, necessitating the 
employment of a boiler. Furthermore, the production 


*7 S 

of ihe gas under pressure necessitated the use of a gas- 
ometer for its collection before it was supplied to the 
engine-cylinder. Such installations were evidently 

costly, and were, moreover, difficult to maintain in 
proper working order. Nevertheless, there are many 
cases in which they must be industrially employed. 




Among these may be cited works in which producer- 
gas is employed as a furnace fuel or as a soldering or 
roasting medium. Still other cases are those in which 
the producer-gas must be piped to some distance from 
a central generating installation to various engines, 
in the manner rendered familiar in gas-lighting prac- 

Most pressure gas-generators have been copied from 
the original type invented by Dowson. These include 
a generator in which the gas is produced; an injector 
fed by a boiler; a fan or a compressor by means of 
which a mixture of steam and air is blown under the 
generator-furnace; washing apparatus termed "scrub- 
bers"; gas-purifying apparatus; and a gas-holder 
(Fig. 77)- 

Generators. — The generator consists of a retort made 
of refractory clay, vertically mounted, and cylindrical 
or conical in form. This retort is protected on its ex- 
terior by a metal jacket with an intermediate layer of 
sand which serves to reduce the heat lost by radiation. 
The fuel is charged through the top of the retort, which 
is provided with a double closure in order to prevent 
the entrance of air during the charging operation. The 
generator rests on a grid arranged at the base of the 
retort, upon which grid the ashes fall. The outlet of 
the injector-pipe opens into the ash-pit, and this injector 
constantly supplies a mixture of steam and air. The 
mixture is generally superheated by passing it through 
a coil arranged in the fire-box of the boiler, in the gen- 
erator, or in the outlet for burnt gases. Sometimes the 


air is subjected to a preliminary heating by recuperat- 
ing in some way the waste heat of the apparatus. 

The chief features in the arrangement of generators 
which have received the attention of manufacturers are 
the following: Good distribution of the fuel in charg- 
ing; easy descent of the fuel; reduction of the destruc- 
tive action of the clinkers on the walls ; means for clean- 
ing the grate without interfering with the generation of 
gas; prevention of leakage. Many devices have been 
employed to fulfil these requisites. 

A perfect distribution of the fuel during charging is 
attained chiefly by the form of the hopper, and of its 
gate, which is generally conical. In most apparatus 
the gate opens toward the interior of the generator, and 
the inclination of its walls causes a uniform scattering 
of the fuel in the retort. It is all the more necessary to 
disperse the fuel in this manner when the cross-section 
of the retort is small compared with its height. 

The facility of the fuel's descent is dependent largely 
upon the nature and the size of the coal employed. 
Porous coal gives better results than dense and compact 
coal. It is therefore preferable to employ screened 
coal free from dust in pieces each the size of a hazel- 
nut. The various sections given to the interior, includ- 
ing as they do cylindrical forms, truncated at the sum- 
mit or the base, partially truncated toward the base 
and the like, would lead to the conclusion that this 
question is not of the importance which some writers 
would have us believe. Still, it must be considered that 
if the fuel drops slowly, its prolonged detention within 





the walls of the hopper and its transformation into 
fusible slag may result in a disintegration of the re- 
fractory lining of the furnace. 

The quantity of steam injected, greater or less, ac- 
cording to the nature of the fuel, renders it possible to 
obtain friable slags and consequently to prevent grave 
injury to the retort. Red-ash coal is in general fusible, 
containing as it does some iron. Its temperature of 
fusion varies between 1,832 to 2,732 degrees F. 

Cleanliness is most important so far as the opera- 
tion of the generator is concerned. It should be pos- 
sible to scrape the generator during operation without 
changing the composition of the gas, when the incan- 
descent zone is chilled, or an excess of air is introduced, 
or the steam-injector be momentarily thrown out of 
operation. Mechanical cleaners with movable grates 
or revolving beds have the merit of causing the ashes 
to drop without interfering with the operation of the 
apparatus. The same meritorious feature is character- 
istic of ash-pits having water-sealed joints. 

Pressure gas-generators need not be as perfectly gas- 
tight as suction apparatus. Leakage of gas, which is 
usually manifested by a characteristic odor, results in a 
loss of consumption and renders the air unfit to breathe. 

A generator should be provided in its upper part 
with openings through which a poker can easily be in- 
troduced in order to shake up the fuel and to dislodge 
the clinkers which tend to form and which cause the 
principal defects in operation, particularly with fuels 
that tend to swell, cake, and adhere to the furnace walls 


when heated. Many apparatus, moreover, are pro- 
vided with lateral openings having mica panes through 
which the progress of combustion can be observed 

(Fig- 79)- 
Air-Blast. — The system by which air and steam are 

Fio. 79. — Ffcbet-Heurtey producer with rotating bed-phte 

injected necessitates the employment of a steam-boiler 
of 75 pounds pressure. This method of blowing, which 
is rather complicated, has the disadvantage of varying 



in feed with the pressure of the steam in the boiler, 
which pressure is not easily maintained at a given num- 
ber of pounds per square inch. Moreover, when more 
or less resistance is offered by the fuel in the generator 
the quantity of air which is injected is likely to be 
diminished in quantity while the quantity of steam re- 
mains the same. The result is a change in speed which 
follows from the modification of the proportions of the 
two elements. For these reasons some manufacturers 

Coating blower. 

have resorted of late years to the employment of fans 
and blowers. 

Blowers. — The fans or blowers employed vary con- 
siderably in arrangement. Most of them are based on 
the Koerting system ( Fig. 80) , and comprise essentially 
(1) a tube through which the steam is supplied under 
pressure, and (2) a cylindro-conical blast-pipe. The 
tube is placed in the axis of the blast-pipe at its outer 
opening. As it escapes under pressure the steam is 
caught in the blast-pipe and draws with it a certain 
quantity of air, which can be regulated. It is important 
that these injection blowers should operate in such a 
manner that the pressure and the feed of air and steam 
can be controlled. 

Fans. — Mechanical blowers have the advantage of 


dispensing with the employment of steam under pres- 
sure and the consequent installation of a boiler (Fig. 
78) . Driven by the engine itself or from some separate 
source of power, these apparatus are easily placed in 
position, require no great amount of attention, and util- 
ize but little energy. They are either of the centrif- 
ugal type or of the rotary type, exemplified in the Root 
blower (Fig. 81). The latter system has the advantage 

Fig. 81. — Rout blow 

of high efficiency, and of enabling comparatively high 
pressures — 19 to 27 inches of water — to be attained, 
which, however, are used only for special fuels, such 
as lignite, peat, and the like. The air supplied by the 
blower, before reaching the fire-box, is superheated, 
either before or after it is charged with steam. 

Compressors.— In some installations air is supplied 
by compressor under the high pressure of 70 to 90 
pounds per square inch, and seem well adapted to the 
production of a gas of good quality. Moreover, neither 



tar nor ammoniacal waters are produced. The Gardie 
producer may be considered typical of this class of ap- 
paratus (Fig. 82). The chief feature of this producer 
is to be found in simple washing and purifying appara- 
tus. It may be well to state here that the compression 
of air at high pressure occasions some complications, 
and a considerable expenditure of power. 

Fig. 82. — Gardic produce 

Exhausters. — Some designers have invented devices 
which draw gas into the generator whence it is sup- 
plied to the engines, these suction apparatus being 
connected with the blowers or used separately- But 
with the exception of a few special instances, such ar- 
rangements are not widely used — at least not for the 
production of motive power alone. 

Whatever may be the arrangement employed for the 

A S. 


introduction of a mixture of air and steam under the 
grate of the generator, the blast-pipe as a general rule 
discharges toward the center of the apparatus. Still, in 
large producers it becomes desirable to provide a means 
for varying the quantity at air and steam within wide 
limits so as to regulate the heat of the fire. For that 
reason several outlets are symmetrically arranged be- 
low the fuel. 
Washing and Purifying.— In pressure producers 

Sawdust purifier. 

the gas is generally washed and purified with much 
more care than in suction apparatus, Given a sufficient 
pressure, the gas can be driven through the different 
apparatus and the spaces between the material which 
they contain without any difficulty. The gases emerge 
from the generator highly heated, and this heat is used 
either to warm the injection water or to generate the 
steam fed to the furnace. The gases then enter the 



washing apparatus, which most frequently consists of 
a succession of contrivances in which the gas is washed 
either by causing it to bubble up through the water, or 
by subjecting it to superficial friction against a sheet of 
water, or by systematically circulating it in a mass of 
continuously besprinkled inert material. The object of 
washing is to remove the dust contained in the gas and 

to precipitate it in the form of a slime which can be re- 
moved by flushing. 

Physical purification thus begun is completed by 
passing the gas through a filtering bed consisting of 
fiber, sawdust, or moss (Figs. 83 and 84). Chemical puri- 
fication, if it is necessarv, is effected by means of cal- 
cium hydrate, iron oxide, or, still better, by a mixture 
of lime and iron sulphate. This filtering material must 
necessarily be renewed after it is exhausted. 


Gas -Holder. — The gas-holder is composed essen- 
tially of a tank and a bell. Sometimes, for the purpose 
of simplifying the apparatus, the tank is so arranged as 

Fig, 85. — Com bin i:d gas-holder and washer 

to take the place of a washer or scrubber (Fig. 85). 
The bell should be provided with mechanism which, 
when the bell is full, automatically diminishes or stops 
the generation of gas. It is advisable to provide the 



bell with a blow or flap valve opening toward the inte- 
rior. If, therefore, it should happen that the gas sup- 
ply is cut off while the engine still continues to run, 
the suction of the engine will not draw the water from 
the tank of the gas-holder. 

When engines are employed the horse-power of which 
does not exceed 50, it is sometimes customary to use 
the water of the tank (placed at a higher elevation than 
the engine) to cool the cylinder. In this manner the 
cost of installing special reservoirs is saved. If such 
an arrangement be employed, however, the quantity of 
water contained in the tank should be at least double 
that ordinarily contained in reservoirs. If this precau- 
tion be not observed, the water may become excessively 
heated and expand the gas in the bell. 

The volume of the bell of the gas-holder should 
preferably be not less than about 3 cubic feet per effec- 
tive horse-power of the engine to be supplied. Under 
these circumstances the bell acts as a pressure-regulator, 
assures a sufficient homogeneity of the remaining gas, 
and renders it possible to supply the engine during the 
short intervals in which it is necessary to stop the blast 
to poke the fire. But if the engine consumes 60 to 
80 cubic feet of producer-gas per horse-power per 
hour, the bell must be very much larger in size if the 
generation of gas is to be checked for some time . 

It may be well to recall here that coal is not the only 
fuel which lends itself to the generation of gas suitable 
for driving engines, but that some generators are able to 
utilize lignite, peat, and the like. In others, straw, 


wood, shavings and sawdust, tannery waste, and other 
organic matter is burnt with an efficiency very much 
higher than that which they would give in the fire- 
boxes of steam-boilers. 

Lignite and Peat Producers.— Lignite and peat 
generators (Fig. 86) cannot operate on the suction 
principle because of the resistance offered to the pas- 
sage of gas by the layer of fuel. This resistance is con- 
siderable and extremely variable. Consequently, lig- 

Fig. 86.— Otto Dcutz lignite-producer. 

nite and peat generators must operate on the pressure 
principle by utilizing a blast of air or a steam injector, 
depending upon the amount of water contained in the 
lignite. As a general rule a Root blower operating at 
a pressure of 8 to 27 inches of water, depending upon 
the quality of the lignite, is employed. These genera- 
tors are not to be recommended for powers less than 
50 horse-power, for the cost of the apparatus becomes 
too great. 


The best lignite is that which, after combustion, 
leaves a fine ash and no agglomerated clinker. Lig- 
nite has the peculiarity of forming dust which ignites 
very easily when air is admitted into the generator. 
For this reason the generator should not be scraped 
during operation, in order to avoid the production of 
a flame which may escape from the apparatus. 

The scrubber is simply a column without coke, 
and is provided with an interior sprinkler. The 
coke is too rapidly clogged with tar. Much of 
this tar is deposited in a chamber which precedes the 
gas-holder. Several quarts of tar may be tapped from 
the chamber dailv. 

The gas-holder serves merely to regulate the pro- 
duction of gas. The pipes leading to the engine should 
be cleaned several times each month, in order to re- 
move the thin layer of tar which is deposited within 

There are many kinds of lignite, and the gas-genera- 
tor should be constructed to meet the peculiar require- 
ments of the variety employed. The layer of fuel 
should be such in thickness that the gas as it emerges 
from the generator has a temperature of about 77 
degrees F. This is the temperature of the gas which 
leaves the scrubber in the case of anthracite-generators. 
If the lignite contains much water, the greater part is 
retained in the washer by the gas in the form of drops. 
Sometimes the water drips through the grate of the 
generator. Lignite-generators may also be operated 
with peat, and even with town refuse, with slight modi- 


fications. The consumption per horse-power per hour 
is 3.3 pounds of lignite containing 2,400 calories 
(9,424.9 B. T. U.). In order to generate the same 
power with a boiler and steam-engine, 8.8 pounds would 
be required. An engine driven unloaded with fuel 
furnished by a lignite-generator will consume 50 per 
cent, of the weight of the fuel required at full load. 
This depends upon the proportion of water contained 
in the lignite and on losses of heat by radiation from the 
generator. In street-gas engines running without load, 
the absorption is 20 per cent., in anthracite-generators 
40 per cent, of the consumption at full load. 

Passing now to the utilization of wood, of which 
something has already been said in Chapter XI, two 
entirely distinct processes are successfully employed in 
apparatus of the Riche type, these processes depending 
upon the form of the wood used — whether, in other 
words, the wood be consumed in the form of sticks or 
blocks or in the form of chips, sawdust, bark, and the 
like, all of them the wastes of factories in which wood 
is used. 

Distilling-Producers. — If the wood consists of logs, 
it is burnt in a generator comprising a fire-box and a 
distilling retort. The fire-box is charged with ordinary 
coal which serves to heat the retort to redness. The 
wood is discharged through the top of the retort, and 
the gas, produced by the distillation, escapes through 
the bottom and passes to the washing apparatus. The 
base of the retort is heated to about 1,652 degrees F., 
while at the top this temperature is reduced to 752 dc- 

grees F. The wood thus treated is transformed into 
charcoal, which is a by-product of some value. 

The lower part of this cast retort (Fig. S7) is lined 
with charcoal, the residue of previous distillations. 

The wood which is introduced in the upper part of 
the retort is distilled in the chamber. The retell i* 

Lheld by its own weight in a socket on the foot, which 
socket is lined with a special refractory cement, made 
of silicate, asbestos forming the joint. The products 


of combustion, issuing from the furnace, pass by way 
of the flue to the lower part of the casing, and raise 
the temperature of the retort and the charcoal it con- 
tains to that of a cherry red (1,652 degrees F.). These 
products of combustion then float to the upper part of 
the casing and heat the top of the retort to a temperature 
of about 752 degrees F., in which part the wood or the 
wooden waste to be distilled is enclosed. Thence the 
products of combustion pass through a horizontal flue, 
provided with a damper, into a collecting flue by which 
they are led to the smoke-stack. The products of distil- 
lation formed in the chamber, having no outlet at the 
top of the retort, must traverse the zone rilled with in- 
candescent carbon. The condensible products are con- 
ducted as permanent gases (carbonic-acid gas in the 
state of carbon monoxide) and are collected in the re- 
ceptacle, after having passed the funnel and the bell of 
the purifying apparatus. 

A gas.-furnace is formed by grouping in a single mass 
of masonry a certain number of elements of the kind 
just described. It is essential that the retorts should be 
vertically placed, that they be made only of cast metal 
and not of refractory clay, and, finally, that their diam- 
eter be not much more than 10 inches, which size 
has been found most expedient in practice. The gas 
collected in the bell or in one or more of the receptacles 
passes into the gasometer and then into the service pipes. 
If 2.2 pounds of wood be distilled by burning in the 
furnace § of a pound of coal of average quality or 2.2 
pounds of wood (either sawdust or waste), 24.5 to 28 



cubic feet of gas will be generated having a thermal 
value of 3,000 to 3,300 calories per cubic meter (1 1,904 
to 13,094 B. T. U. per 35.31 cubic feet), and a residue 
.44 pounds of charcoal will be left. 

In practice only the wood of commerce containing in 
the green state 20 to 40 per cent, of water, depending 
upon the variety, is used. Hornbeam contains the least 
water (18 per cent.), while elmwood and spruce con- 
tain the most (44 to 45 per cent.). 

The blast apparatus of the generator being started, 
the gas is supplied under pressure. By reason of its 
permanent composition and its richness, it is an excel- 
lent substitute for street-gas in incandescent lighting, 
a good furnace fuel reducing agent. 

Producers Using Wood Waste, Sawdust, and the 
Like. — If waste wood in the form of shavings, sawdust, 
straw, bark, and the like, should be employed, a still 
higher efficiency is obtained with self-reducing genera- 
tors of the Riche type. 

Combustion-Generators. — In combustion-generators 
(Fig. 88) the fuel is burnt and not distilled. The gen- 
erator comprises two distinct elements. The first is the 
generator proper, in which the combustion takes place. 
Upon it is placed a hopper or fuel supply box. The 
second element is the reducer, in which by an independ- 
ent process the reduction of the carbonic-acid gas, the 
dissociation of the steam, and the transformation of the 
hydrocarbons takes place. The generator is provided 
at its base with a grate having oblique bars in tiers, 
which grate is furnished with a channel in which the 


water for the generation of hydrogen flows. On a level 
with this grate, at the opposite side, is a flue com- 
municating with the reduction column of coke. The 
incandescent zone of the generator should not extend 
above the level of the grate. Instead of passing through 
the layers of fresh fuel and out by way of the top, the 
gas generated flows directly into the reduction column 
where it heats the coke to incandescence. The high 
temperature to which the coke is subjected, coupled 
with the injection of air, effects useful reactions. This 


additional air, however, is not used if the fuel is free 
from all products of distillation. 

Experience has shown that gas of 1,000 to 1,100 cal- 
ories per cubic meter (3,968 to 4,365 B. T. V. per 3 ^.31 
cubic feet), which heat content is necessary to develop 
one horse-power per hour, can be obtained with 3.96 
pounds of wood in the form of shavings and sawdust 
containing 30 per cent, of water. The corresponding 
quantity of coke consumed in the reduction column is 


insignificant, and may be placed at about 0.1 12 pounds 
per horse-power per hour. 

It has been proven in actual practice that, both in 
the distilling and combustion types of apparatus, the 
wood, either in the green state or in the form of saw- 
mill waste, may contain as much as 60 per cent, of 
water. Either of the two systems can be operated under 
pressure with an air-blast, in which case a gas-holder 
and bell must be employed. The gas as it passes from 
the generator to the gas-holder is conducted through a 
cooler and washer and through a moss filter, which 
removes traces of the products that may have escaped 
the distillation. 

Inverted Combustion. — With a few exceptions the 
pressure-generators which have been described, as well 
as suction gas-producers which will be later discussed, 
are fed with anthracite coal or with coke. They cannot 
be operated with moderately soft or bituminous coal. 
For this reason they limit the employment of producer- 
gas engines- Manufacturers have long sought genera- 
tors in which any fuel whatever can be consumed. 

Among the producers which seem to overcome the 
objections cited to a certain degree, are those which are 
based on the principle of inverted combustion. These 
apparatus embody the ideas of Ebelmen, the products 
of distillation being decomposed by passing them over 
layers of incandescent fuel. 

Many writers place in the class of inverted combus- 
tion producers, apparatus of the Riche, Thwaite, and 
Duff type, in which this idea is also carried out. Riche 

i 9 7 

employs an independent incandescent mass to reduce 
the products of distillation of another mass. Thwaite 
employs two vessels which serve alternately as distilling 


retorts and reducing columns. Duff draws in the prod- 
ucts of distillation for the purpose of blowing them 
under the fire. All these generators can hardly be said 
to be of the inverted combustion type. 


The generators of Deschamps (Fig. 89) and of 
Fange and Chavanon (Fig. 90), on the other hand, are 
producers in which the combustion is really inverted, 
and which are worked continuously. The air enters at 
the upper part of the retort, passes through the entire 
mass of fuel, carrying with it the distilled volatile prod- 
ucts, and when the mixture reaches the incandescent 
zone, chemical reactions occur that result in the pro- 
duction of a gas entirely free from tar and other im- 



The high cost and the complicated nature of the 
pressure gas-generators which have just been discussed 
have led manufacturers to attempt in some other way 
the generation of producer-gas intended for operating 

Several inventors, among whom we will mention 
Benier and A. Taylor (in France), made some praise- 
worthy although not immediately very successful at- 
tempts to simplify the manufacture of producer-gas. 

Advantages. — In these systems the suction occa- 
sioned by the motor itself has taken the place of a forced 
draft, produced in the generator by an air-injector or a 
fan, so that the gas, instead of being stored under pres- 
sure in a gas-holder, is kept in the apparatus under a 
pressure below that of the atmosphere. 

As the device for producing a draft by means of 
boiler pressure or of a fan, and the gas-holder, are dis- 
pensed with, the result is a saving, first in the cost of 
installation, consumption, and floor space. Further- 
more, the cooler and washer are supplanted by a single 

Manufacturers have succeeded in devising apparatus 
remarkable for the simplicity of the processes employed 


and yielding economical results which would never be 
obtained with pressure-generators employing gas-hold- 
ers and boilers, considering that the boiler alone calls 
for a consumption of from 1 5 to 30 per cent, of the total 
amount of coal used for making the gas. 

The best results obtained by the author with pressure 
gas-producers have indicated a consumption of not 
much less than 1 to 1 r 4 pounds of anthracite per horse- 
power per hour at the motor, while with suction-gen- 
erators, under similar conditions and with the same 
grade of fuel, he has repeatedly found a consumption 
of from A pounds per effective horse-power per hour. 
In either case, the gas obtained developed between 
1,100 and 1,300 calories (4,365 and 5,158 B. T. U. 
per 35.31 cubic feet) if produced from anthracite yield- 
ing from 7,500 to 8,000 calories (29,763 to 31,746 
B. T. U.) per 2.2 pounds. 

The suction apparatus will also work very well with 
inferior coal containing up to 6 to 8 per cent, of volatile 
matter and from 8 to 10 per cent, of ash. This great 
advantage added to all the others explains the favorable 
reception which European manufacturers at once gave 
to suction-producers. The petroleum engine itself will 
find a serious competitor in the new system. 

As regards the possibility of employing suction gas- 
generators with respect to the somewhat peculiar prop- 
erties of the fuel, it may be said at the outset that coke 
from gas works yielding from 6,000 to 6,500 calories 
(22,911 to 24,995 B. T. U.) and also charcoal are per- 
fectly available. 


One hurse-power per hour is obtained with a con- 
sumption of i.i to 1.3 pounds of coke. 

Blast-furnace coke mav be used in case of need, but 
its employment is not to be recommended on account of 
the sulphides it contains, which sulphides, being car- 
ried along by the gas, are liable to form sulphuric acid 
with the steam, the corrosive action of which would 
soon destroy the cylinder and other important parts of 
the engine. 

Qualities of Fuel.— Anthracite coal is, upon the 
whole, so far the best available fuel for generators. 
However, it should possess certain qualities which will 
now be briefly indicated. 

In suction gas- gen era tors, above all, it is important 
that no harmful resistance should be opposed to the 
passage of the air and of the gas produced. It is there- 
fore necessary to employ coal of a size that will an- 
swer the foregoing condition, without being too expen- 

The size of the pieces, to a certain extent, determines 
the price; and with coal of the same properties, pieces 
i.i to 2 inches may cost 1.4 of the price for the ordinary 
size of 0.59 to 0.98 inches, which is very well adapted 
for gas-generators. This is the size of a hazel-nut. 

Moreover, it will be advisable to select the dryest 
coals, containing a minimum of volatile matter and hav- 
ing no tendency to coke or to cohere, in order that the 
volatilized products may not by distillation obstruct the 
interstices through which the gases must pass. For the 
same reason coal which breaks up and becomes pulver- 


ized under the action of the fire is not to be recom- 
mended. The coal should also be such as to avoid the 
formation of arches which would interfere with the 
proper settling of the fuel during its combustion. It 
may be stated as a rule that, with coal that does not co- 
here, the content of volatile matter should not exceed 
5 to 8 per cent. 

Coal which contains more than 10 to 15 per cent, 
of ash should not be used, for the reason that it chokes 
up and obstructs generators in which the dropping and 
discharge of the ashes is done automatically, a fact 
which should not pass unnoticed. The furnace cannot 
be cleaned safely with a fire of this kind, where com- 
bustion takes place in an enclosed space, without hin- 
dering the production of gas. Here again a point may 
be raised' very much in favor of suction gas-producers. 
In a good generator, the ash-pit can be cleaned and the 
fire stoked without interrupting the liberation of the 
gas drawn in and without appreciably impairing the 
quality of the gas. These considerations are of im- 
portance so far as the gas-generator itself is concerned. 
Other conditions which should be noticed affect the 
engine fed by the generator, the grade of coal used, and 
the purification of the gas obtained from it. 

Unless special chemical cleaners and purifiers are 
employed, thereby complicating the plant, the coal 
utilized should yield as little tar as possible during dis- 
dilation; for the tendency of the tar to choke up the 
pipes and to clog the valves is one of the chief causes of 
defective operation of producer-gas engines. 


Tar changes the proper composition of the explosive 
mixture. When it catches tire in the cylinder it causes 
premature ignition, which is so dangerous in large en- 

From what has been said in the foregoing, it follows 
that, in the present state of the art, the satisfactory 
operation of gas-generators depends no longer on the 
use of pure anthracite, such as Pennsylvania coal in 
America and Welsh coal in England, containing an 
amount of carbon as high as 90 to 94 per cent, and hav- 
ing a thermal value of 33,529 B. T. U. On the con- 
trary, good dry coal yielding from 29,763 to 31,746 
B. T. U. is quite suitable for the generation of pro- 

A final, practical advantage which speaks in favor of 
a generator and motor plant as compared with a steam- 
engine, is the small amount of water required. Apart 
from the water used for cooling the engine, which may 
be used over and over again if cooled, any water, 
whether it forms scale or deposits, may be employed for 
cooling and washing the gas in the scrubber. 

According to the authors personal experience, an 
average of 2i gallons of water per effective horse- 
power per hour is sufficient for this purpose. This is 
about one-half of the amount required by a non-con- 
densing slide-valve engine of from 15 to 30 horse- 
power. The difference in the consumption of water is 
quite important in city plants, where water is rather 
expensive as a rule. 

General Arrangement. - 

-A suction gas-generator 


plant of the character we have been discussing is shown 
in Fig. 91. 

The apparatus A is the generator proper, in whic 
combustion takes place. The gas produced passes into 
the apparatus li through a series of tubes, to be con- 
veyed to the washer C. In the apparatus 13, which is 
the vaporizer, the water admitted at the top under at- 
mospheric pressure is vaporized by contact with a serie 
of tubes, heated by the gas coming from the generator." 

In,. <)i. — tngine and 

The steam, together with air, is drawn into the lower 
part of the generator to support combustion. This vapor- 
izer is provided with an overflow for the outlet of the 
water which has not been vaporized. The producer- 
gas pipe which leads from the vaporizer to the washer 
has a branch D, for the temporary escape to the atmos- 
phere of the gas produced before and after the opera- 
tion of the engine. In the washer, as the drawing 
shows, the gas enters at the bottom and leaves at the tc 
to pass to the gas expansion-chamber E and thence 1 
the motor. The gas thus passes through the body of 



of r 

coke in the opposite direction to the wash water, which 
then flows to the waste-pipe. The coke and the water 
free the gas not only from the dust carried along, but 
from the ammonia and other impurities contained in 
the gas. 

When firing the generator, a small hand ventilator 
G is used for blowing in air to fan the fire. The gas 
obtained at first, being unsuitable for combustion, is 
allowed to escape through the branch D. After in- 
jecting air for about 10 to 15 minutes, the engine can 
be started after closing the branch D. The suction of 
the engine itself will then gradually bring about the 
proper conditions for its regular running, and after a 
quarter of an hour or half an hour the gas is rich 
enough to run the engine under a full load. 

The apparatus just described is the original type, 
upon which many improvements have been made for 
the purpose of securing a uniform gas production and 
of diminishing the interval of time elapsing between 
the firing of the generator and the running of the en- 
gine under a full load. 

Each of the elements of this apparatus — to wit, the 
generator, vaporizer, superheater, and washer — have 
been modified and improved more or less successfully 
by the manufacturers ; and in order that the reader may 
perceive the merits and the drawbacks of the various 
arrangements adopted, the most important ones will be 
separately discussed. 

Generator. — With respect to the general arrangement 
of parts, generators may be divided into two classes: 


First.— Generators with internal vaporizers, such as 
the Otto Deutz and Wiedenfeld generators. 

Fig. 92. — Old type 


Second. — Generators with external vaporizers, sucl 
as the Taylor, Bollinckx, Pintsch, Kinderlen, Ben 
Wiedenfeld, H tile, and Goebels generators. 


Cylindrical Body. — The generator consists essen- 
tially of a mantle made of sheet-iron or cast-iron and 
containing a refractory lining which forms a retort, a 
grate, and an ash-pit. In the small size apparatus the 
cast-iron mantle is often used, whereas in large sizes 
the mantle is made of riveted sheet-iron so as to reduce 
its weight and its cost. In the latter case the linings 
are securely riveted or bolted. 

The Winterthur generator (Figs. 92 and 93), the 
Taylor generator (Fig. 94), and the Benz generator 
(Fig. 97), are made of cast-iron; the Wiedenfeld gen- 
erator (Fig. 95), the Pintsch generator (Fig. 96), are 
made of sheet-iron; the Bollinckx (Fig. 98) is made 
partly of sheet-iron and partly of cast-iron. 

The different parts of a generator, if made of sheet- 
iron, are held together by means of angle-irons form- 
ing yokes, and a sheet of asbestos is interposed. If the 
parts are made of cast-iron, they are connected after the 
manner of pipe-joints and packed with compressed as- 
bestos. This latter way of assembling the parts pre- 
sents the advantage of allowing them to be dismem- 
bered readilv. Therefore, it allows the several parts to 
expand freely and facilitates the securing of tight joints. 
This last consideration is exceedingly important, par- 
ticularly for the joints which are beyond the zone in 
which the distillation of the fuel takes place. Any en- 
trance of air through these joints would necessarily im- 
pair the quality of the gas, either by mingling there- 
with, or by combustion. The air so admitted would 
also be liable to form an explosive mixture which might 


become ignited in case of a premature ignition of the 
cylinder charge during suction or through some other 

Refractory Lining. — The interior lining of the gen- 
erator should be made of refractory clay of the best 

Fig. 99.— Lcncauchcz producer. 

quality. It would seem advisable, in order to facilitate 
repairs, to employ retorts made of pieces held together 
instead of retorts made of a single piece. In the first 
case the assembling should preferably be made by 
means of refractory cement, and the inner surface 


should be covered with a coating so as to form a prac- 
tically continuous stone surface. 

Some manufacturers, in order to allow for the re- 

Frc. ioo. — Goebels prodi 

newal of the part most liable to be burnt, employ at the 
bottom of the tank a refractory moulded ring (Len- 
cauchez, Fig. 99). 

It is always advisable to place between the shell < 


Grate and Support for the Lining.— These parts, 
owing to their contact with the ashes and the hot em- 
bers, are liable to deteriorate rapidly. It is therefore 
indispensable that they should be removable and easily 
accessible, so that they may be renewed in case of need. 
From this point of view, grates composed of inde- 
pendent bars would appear to be preferable. The 
clearance between the bars depends, of course, on the 
kind of ashes resulting from the different grades of 
fuel. It is advisable to design the grate so that the free 
passage for the air is afjout 60 to 70 per cent, of the 
total surface. 

In generators having a cup-shaped ash-pit, .contain- 
ing water (Fig. 95), the grate and the base of the re- 
tort are less liable to burn than in apparatus having dry 
ash-pits. Certain apparatus, such as those of Lencau- 
chez (Fig. 99), Pierson (Fig. 101), and Taylor (Fig. 
94) , have no grates ; the fuel is held in the retort by the 
ashes, which form a cone resting on a sheet-iron base, 
easy of access for cleaning and from which the fuel 
slides down gradually. 

The Pierson generator (Fig. 101) is provided with 
a poker comprising a central fork, which is worked 
with a lever, in order to stir the fire from below with- 
out entirely extinguishing the cone of ashes. 

In some apparatus in which a grate is used (Fig. 92), 
a space is left between the grate and the support of the 
retort. This arrangement has the merit of allowing 
only finely divided and completely burnt ashes to pass 
to the ash-pit. Moreover, a large surface grate can be 


employed, thus facilitating the passage of the mixture 
of air and steam. 
The space above mentioned is provided with a clean- 


Fig. 102. — Kidcrlcn prod 

ing-door through which cinder and slag may be re- 

In other apparatus the grate rests either on the sup- 
port of the refractory lining, as in the old type invented 



by Wiedenfeld (Fig. 95), or upon a projection em- 
bedded in the lining, as, for instance, in the Kiderlcn 
(Fig. 102) and Pintsch generators (Fig. 96). 

In the Riche apparatus (Fig. 103) there is, besides 
the ordinary grate, a grate with tiers on which the fuel 

Fig. 103.— Riche combust ion- prod uc 

spreads. This grate consists of wide, hollow bars con- 
taining water, It should be noted that the apparatus is 
of the blower type. 

An interesting arrangement is found in Benier's gen- 
erator (Fig. 104). This consists of a grate formed of 
projections cast around a cylinder which can be turned 
about its axis. The finely divided ashes which are re- 



tained in the spaces between these projections are thus 
carried into the ash-pit, and those which adhere to the 
metal are scraped away by a metallic comb fastened to 

Fig. 104. — Bonier producer. 

the lower part of the apparatus. The " Phcenix " gen- 
erator {Fig. 105) is fitted with a grate having a 
mechanical cleaning device, worked by a lever from the 
Ash-Pit. — The ash-pits are exposed to the destructive 


effects of heat and moisture, and should preferably be 
constructed of cast-iron, since sheet-steel is liable to 

corrode quickly. 

Fig. 106.— Otto Deutz produi 

In most apparatus the ash-pit is hermetically sealed, 

and the air for supporting combustion enters below the 


grate through a pipe leading from the heater or the 
vaporizer. This arrangement seems best adapted to 
prevent the leakage of gas which tends to take place by 
reaction after each suction stroke of the engine. 

Ash-pits formed as water-cups, such as the Deutz 
(Fig. 106), the Wiedenfeld (Fig. 95), and the Bol- 
linckx (Fig. 98), are fed by the overflow from the 
vaporizer. These ash-pits are themselves provided 
with an overflow consisting of a siphon-tube forming i 

Besides providing protection to the grate and other 
parts by this sheet of water, a larger proportion of the 
heat radiated from the furnace is utilized for the pro- 
duction of steam which contributes to enrich the gas. 
The doors of the ash-pits and their fittings are likewise 
exposed to a rapid deterioration. 

For this reason these parts should be very strongly 
made, either of cast-iron or cast-steel. Furthermore, 
they should, at joint surfaces, be connected in an air- 
tight manner, which may be attained by carefully fin- 
ishing the engaging surfaces of the frame and the door 
proper, or by cutting a dovetail groove in one of the 
sides of the frame which is packed with asbestos and 
adapted to receive a sharp edged rib on the other part. 

The pintles of the hinges should also be carefully 
adjusted so that the joint members of the door shall re- 
main true. Hinges with horizontal axes seem to be 
preferable in this respect to those having vertical axes. 
As a means of closing the door, the arrangement here 
shown (Fig. 107) seems to assure a proper engagement 


of the joint surfaces. It consists of a yoke which strad- 
dles the door, and which, on the one hand, swings about 
the hinge, and on the other hand engages a movable 
hoop. A screw, fastened to the yoke, serves to tighten 
the door by pressure on its center. This screw can also 
be fastened to the end of the yoke (Fig. 108). 

It is very advantageous to provide in each door a 
hole closed by an air-tight plug, so that in case of 


Figs. 107-108.— Fire-box doors. 

need a tool may be introduced for cleaning the grate. 
In this manner the grate may be cleaned without 
opening doors and without causing a harmful entrance 
of air. 

The door of the furnace, particularly, should be pro- 
vided with an iron counter-plate held by hinged bolts 
(Fig. 109) ; or, better still, this door should be so con- 
structed that it can be lined with refractory material to 
protect it against the radiated heat of the fire. 

Charging-Box. — Like the other parts of the genera- 
tor the construction of which has been discussed above, 
the charging-bo.\ should be absolutely air-tight. 


On account of their greater security, preference 
should be given to double closure devices, which form 
a sort of preliminary chamber, o\ving to which the fill- 
ing of the generator is made in two operations. The 
first operation consists in filling the preliminary cham- 
ber after opening the outer door. Upon closing this 
outer door, the second operation is performed, which 
consists in moving the inner door so as to cause the fuel 
in the preliminary chamber to drop into the generator. 

Fig. 109. — Door with refractory lining. 

Stress has been laid on the greater safety of this type of 
charging-box for the reason that, with devices having a 
single charging-door, a sudden gust of air may rush 
in at the time of charging the furnace, and bring about 
an explosion very dangerous to the workman entrusted 
with stoking the furnace. 

The closure is generally simply a removable cover, 
or may be a lid swinging about a hinge having a hori- 
zontal or vertical axis. 

As regards the inner door, which is of great im- 
portance, in order to insure an air-tight joint, there 1 
three chief types of closure: 



i. The Lift- Valve. 

2. The Slide-Valve. 

3. The Cock. 

The Lift-Valve.— The lift-valve is formed by a disk 
of conical or spherical shape moved up and down by 
means of a lever having a counter-weight for adjust- 
ment. The valve is used in the Winterthur (Fig. 92) 
and Bollinckx (Fig. 98) generators. 

This device serves as an automatic closure and insures 
a tight joint irrespective of wear. Moreover, it presents 
the advantage that, at the moment of opening, it dis- 
tributes the fuel evenly in the generator; but on the 
other hand, it has the drawback of not allowing the 
fuel to be examined or shaken through the charging- 
box. In apparatus provided with this kind of valve, it 
is therefore advisable to furnish the upper part ot the 
generator with agitating holes closed by an air-tight 

Slide-Valve. — The slide-valve closure consists of a 
smooth-finished metallic plate movable below the 
charging-box proper. Operated as it is from the out- 
side, it is evident that the slightest play, the wearing of 
the pivot, or the weight of the charge, will form spaces 
between the plate and its seat through which air may 
rush in. 

Furthermore, the manipulation of the slide-valve 
may be interfered with if too much fuel is put in the 

The valve or damper may move parallel to itself or 
swing about the operating axis. The Taylor apparatus 


(Fig. 94) and the Benier apparatus {Fig. 104) are 
provided with such valves. 

The Pintsch generator (Fig. 96) is provided with a 
device which, properly speaking, is not a damper, but 
which consists of two boxes movable about a vertical 
axis and arranged to be displaced alternately above the 
shaft to effect the charging. This system effects only 
a single closure, but explosions are scarcely to be feared 
with an apparatus of this kind, owing to the consider- 
able height of fuel contained between the charging 
opening and the gas-producing zone. 

Cock. — The cock is applied particularly in the mod- 
ern apparatus of the Otto Deutz Co. (Fig. 106) and 
the Pierson generator (Fig. 101 ). It consists of a large 
cast-iron cone, having an operating handle and an 
opening. The cone moves in a sleeve formed by the 

This arrangement appears to be preferable to the 
others on account of its simplicity and of the case with 
which it can be taken apart for cleaning. Moreover, 
the fuel can be poked directly through the feed-hopper. 
In apparatus provided with a cock, it is advisable to 
place on the outside cover a mica pane through which 
the condition of the fuel may be examined without 

Feed-Hopper. — Below the charging-box is arranged, 
as a rule, a hopper tapered conically downward. This 
part of the generator should serve only as a storage 
chamber for fuel. It can therefore be made of cast- 
iron, and has the advantage of being removable, easily 




replaced, and of allowing ready access to the retort for 
the purposes of examination and repair. 

The annular space surrounding this feed-hopper gen- 
erally forms a chamber for receiving the gas produced, 
as in the Winterthur (Fig. 92), the Bollinckx (Fig. 
98), and the Taylor apparatus (Fig. 99). 

In generators having an internal vaporizing-tank, 
this tank itself serves as a feed-hopper, which is the 
case in the Deutz apparatus (Fig. 106) and YVieden- 
feld generator (Fig. 95}. 

Connection of Parts. — In order to facilitate the 
thorough cleaning of the retort, preference is given to 
removable charging-boxes and feed-hoppers. These 
are features of apparatus of the Bollinckx type (Fig. 
98), in which the charging-box is secured to the gen- 
erator by means of its yoke and by catches provided 
with knobs, and also of apparatus of the Winterthur 
kind (Fig. 92), having a charging-box pivoted about 
a vertical axis, or apparatus of the Duplex type (Fig. 
no), in which the charging-box can swing about a 
horizontal hinge. 

Air Supply. —We have seen that, when starting the 
generator, the gas is produced with the aid of a fan. 
This fan may be operated mechanically, but is generally 
operated by hand. 

It is customary to convey the air-blast through a pipe 
leading to the ash-pit, as in the Winterthur apparatus 
(Fig. 92}. Often, however, the air supply pipe is di- 
rectly branched on that which leads from the vapor- 
izer to the ash-pit, as in the Deutz apparatus (Fig. 


106). In this case a set of valves or dampers permits 
the disconnection of the fan or its connection with the 

In some apparatus an air inlet is provided imme- 
diately adjacent to the ash-pit. This arrangement is 
faulty for the reason that it gives rise to gaseous emana- 
tions which take place by reaction after each suction 

Duples chat-pug- hopper. 

stroke of the engine. Furthermore, it is advisable that 
the air supplied below the ash-pit be as hot as possible. 
For this reason the employment of preheaters is desir- 
able. The dry air forced in by the fan stimulates com- 
bustion, and the hot gas produced and mixed with 
smoke escapes through a separate flue, generally ar- 
ranged beyond the vaporizer and serving as a chimney. 
This chimney should in all cases be extended to the 
outside of the building, and should never terminate in 


a brick chimney or similar smoke-flue. The direct 
escape of such gas and smoke through a telescopic 

chimney above the charging-hox has been generally 
abandoned in modern structures. 


The escape-pipe mentioned, being branched on the 
gas-pipe leading to the engine, should be capable of 
disconnection when desired, by a thoroughly tight sys- 
tem of closure. For this purpose, some employ a simple 

-Olio Deutz flue. 

cock (Bollinckx, Fig. in), a three-way cock, a set of 
cocks, or, still better, a double valve, as in the Winter- 
thur apparatus (Fig. 112) and the Deutz apparatus 
(Fig. 113). A double seated valve is also used, as is 
the case in the Benz generator (Fig. 114). 



Vaporizer-Preheaters. — As has been stated before, 
there are vaporizers internal or external, relatively to 
the generator. 

Internal Vaporizers. — The Deutz apparatus (Fig. 
106), for example, consists of an annular cast-iron tank 
mounted above the retort of the generator. 

The hot gases given off by the burning fuel travel 
around this tank and vaporize the water which it con- 
tains. The air drawn in by the suction of the engine 
enters through an opening located above the tank, 
travels over the surface of the water which is being 
vaporized, and thus laden with steam passes to the 

The tank in question is supplied with water by means 
of a cock having a sight feed, located on the outside, 
and the level is kept constant by means of an overflow 
tube leading to the ash-pit. It is well to bend this tube 
and to place a funnel on its lower member. The 
amount of overflow may thus be regulated. 

These vaporizers are simple and take up little room; 
but thev are open to the apparently well-founded objec- 
tion that they heat up slowly and require a considerable 
time to produce the steam necessary to enrich the gas, 
this being due to the relatively large mass of cast-iron 
and the amount of water contained therein. 

The Pierson vaporizer (Fig. 101) and the Chavanon 
vaporizer (Fig. 115) both consist of an annular tank 
forming the base of the generator. Steam is formed 
near the outlet of the ashes, which, as has been described 
above, leads to the outer air. The development of 


steam is regulated by mechanical means controlled by 
the suction of the engine. 
External Vaporizers.- — External vaporizers are gen- 

Fig, 115. — Chitvation produi 

erally formed by a cylinder with partitions constituting 
two series of chambers. In one of these the hot gases 


from the generator travel, and in the others the water to 
be vaporized is contained. 

Tubular Vaporizers.— Different types of tubular 
vaporizers are manufactured. The vaporizer with a 
series of tubes, as in Taylor's apparatus (Fig, 116), 

Fig. i i 6.— Taylor vaporizer. 

Fig. 117.— Deutz vaporiser. 

Deutz's old model (Fig. 1 17) , or with single tube like 
Pintsch's generator (Fig. 118), is formed by three com- 
partments separated by two tube sheets or by plates 
which are connected by tubes. 

In some cases the gases pass within the tubes, while 
the water to be vaporized surrounds them; as in the 


Pintsch apparatus (Fig. n8), and Taylor apparatus 
(Fig. 116), Benz (Fig. 119), and Kocrting genera- 
tors (Fig. 120). 

In other cases, the water lies inside and the gas out- 

side. In this latter case, a longitudinal baffle is em- 
ployed to compel the gases to heat the tubes in their 
whole length, as in the Deutz producer (Fig. 117). In 
a general way it may be said that such a series of tubes 

2 33 

presents the disadvantage of becoming clogged up 
rapidly by the deposit of lime salts contained in water. 
If the set of tubes consists of fire-tubes, the deposit 
will form on the outer surface, that is, on a portion not 
accessible for cleaning. From this point of view, 

KoL-rtinj; vaporizer. 

water-tubes are preferable, as they allow the deposit or 
scale to be removed through the tubular heads or plates. 
On the other hand, such water-tubes have the draw- 
back that their exterior surfaces are readily covered 
with pitch and soot. The tubular vaporizers of the 

a 3 4 


Field type (Bollinckx, Fig, 98) are composed of a 
single sheet-iron tube or shell, in which the tubes are 
arranged, dipping into a chamber through which the 
hot gases pass, This arrangement insures a rapid pro- 
duction of steam, but the Field tubes are even more 
li?ble than the others to become covered with deposits. 

It will be seen that these types of vaporizers should 
all present the following features: easy access, small 
quantity of the body of water undergoing vaporization, 
and large heating surface with small volume. 

The use of copper or brass tubes should be strictly 
avoided, as they would be quickly corroded by the 
action of the ammonia and hydrogen sulphide con- 
tained in the gas. 

Partition Vaporizers. — Partition vaporizers- com- 
prise a cylindrical shell, generally made of cast-iron 
and having a double wall in which the water to be 
vaporized circulates. The gas coming from the gen- 
erator passes into the central portion, where it comes in 
contact with a hollow baffle, also containing water 
(Wiedenfeld, Fig. 121). Vaporizers of this kind are 
strong, simple, and easily cleaned. 

Operation of the Vaporizers.— The general pur- 
pose of vaporizers, whatever their construction may be, 
is to produce steam under atmospheric pressure, by- 
utilizing the heat of the generator gases immediately 
after their production, or, as in the Chavanon system, 
by utilizing the heat radiated from the furnace. 

The air drawn by the engine through the generator 
generally passes through the vaporizers and becomes 



laden with a certain amount of steam which it carries 
along. The amount thus taken up depends chiefly upon 
the temperature and the amount of gases coming from 
the generator, so that the greater the amount drawn into 


Fig. iai— WiedcnfcM vapo 

the engine, the more energetic will the vaporization be, 
and the richer the gas will become. It will be under- 
stood that when a generator is working at its maximum 
production, the interior temperature is highest and 
most favorable to the decomposition of the largest 
amount of steam. 


It follows that with the very simple vaporizers whil 
have been reviewed, a practically automatic regulation 
is obtained. However, some manufacturers have 
deemed it advisable to regulate the amount of ste; 
more accurately, and to make it exactly proportional 
to the power developed by the motor. Thus 
Wintcrthur gas-producer (Figs. 92 and 1 12) the mam 
facturers have omitted the vaporizer proper, and u: 
instead an air-heater and a super-heater for air and 

The heater is formed by a cast-iron box having two 
compartments, through one of which the hot gases from 
the generator pass, while in the other the air intendi 
to support combustion travels. At the inlet of 
super-heater a pipe terminates, which feeds, drop by 
drop, water supplied by a feed device to be described 
presently. This water is vaporized immediately upi 
contact with the wall of the super-heater and is carrii 
along with the air contained in it. 

The super-heater comprises a hollow ring-shaped 
cast-iron piece arranged in the chamber of the genera- 
tor, in which the gases are developed, and is thus heated 
to a high temperature. The mixture of air and steam 
circulates in this super-heater before traveling to thi 

The feeder of the Winterthur gas-generator (Fig. 
122) is composed of a receptacle having the shape of 
tank or basin containing water and located below 
closed cylindrical box, In this box a piston moves, 
which is provided at its lower end with a needle-valve. 







The upper portion of the box communicates with tliu 
gas-suction pipe through a small tube. At each suction 
stroke of the engine, according to the force of the suc- 
tion, the needle-valve piston rises more or less and thus 
allows a variable amount of water to pass. 

Winterthur feeders. 

This apparatus — and all those based on the same 
principle — presents the advantage of proportioning the 
amount of water to the work of the engine; but in view 
of its rather sensitive operation it must be kept in per- 
fect repair and carefully watched. Obviously, should 
the water contain impurities, the needle-valve will bind 


or the orifices will be obstructed, and thus the feeding 
of the water will be interrupted. This will not only re- 
sult in the production of a poorer ga$, but will lead to 
greater wear of the grates, which in this case are not 
sufficiently cooled by the introduction of steam. 

Fig. 123— Hille prodi 

Air-Heaters. — The preliminary heating of the air 
appears to be of great utility for keeping up a good fire. 
This heating is very easily accomplished, and is gen- 
erally effected by utilizing a portion of the waste heat 
of the gases, a procedure which also has the advantage 
of cooling the gases before they pass through the wash- 
ing apparatus. 



The heating of the air for supporting combustion 
takes place either before the addition of steam (Hille's 
generator, Fig. 123), or after the mixture as in Wieden- 
feld's apparatus (Fig. 95). In the first case, the air 
passes through a sheet-iron shell concentric with the 
basin of the generator, is there heated by the radiated 
heat, and is conveyed to the ash-pit by a tube into which 
leads the steam-supplv pipe extended from the vapor- 
izer. In the second type of heater, the mixture of air 
and steam is super-heated du ring its passage through an 
annular piece arranged in the ash-pit of the generator. 


Dust-Collectors. — Dust- collectors are generally 
placed between the generator and the scrubber or 
washer. They may be formed of baffle-board arrange- 
ments against which the gases laden with dust impinge, 
causing the dust to be thrown down into a box provided 
with a cleaning opening (Benz, Fig. 124, and Pintsch, 
Fig. .18). 

Some collectors are formed either bv the vaporizer 
itself, terminating at its base in a tube which dips into 
water and forms a water-seal, as in the Wiedenfeld gen- 
erator (Fig. 121), or by a water-chamber into which 
the gas-supply tube slightly dips {Bollinckx, Fig. ill). 


With this arrangement, the gas will bubble through the 
water and will be partly freed of the dust suspended in 
it. These water-chambers are generally fed bv the 
overflow from the spray of the scrubber. There is thus 
produced a continuous circulation by which the dust, 
in the form of slime, is carried toward the waste-pipe or 

Cooler, Washer, Scrubber.— Some manufacturers 
cool the gas in a tower with water circulation. Most 
manufacturers, however, simply cool the gas in the 
washer or scrubber. This apparatus comprises a cy- 
lindrical body of sheet-iron or cast-iron formed of two 
compartments separated by a wooden or iron grate or 
perforated partition. The upper compartment up to 
a certain level contains either coke, glass balls, stones, 
pieces of wood, and the like. The top of the compart- 
ment is provided with a water supply in the nature nf 
a sprinkler or spray nozzle. The lower compartment 
of the scrubber serves to collect the wash-water which 
has passed through the substance filling the tower. An 
overflow in the shape of a siphon, provided with a water 
seal, carries the water to the waste-pipe either directly 
or after it has first passed through the dust collector. 

The gas drawn in enters the washer in the lower com- 
partment either above the water level (Deutz, Fig. 
125; Winterthur, Fig. 126), or through an elbow 
which dips slightly into the water (Benz, Fig. 127; 
Fichet and Heurtey producer, Fig. 128). 

The gas passes through the grate or partition which 
supports the material filling the tower, and travels 


through the interstices in a direction opposite to that of 
the water falling from the top. Under these conditions, 
the gas is cooled, gives up the ammonia and the dust 

125— Otto Deuta scrubber. 

which it may still contain in suspension, and is conveyed 
to the engine either directly or after passing tlimugh 
certain purifiers. Care should be taken to place the 


pieces of most regular shape along the walls, so that 
the unevenness of their surfaces may not form upward 

channels along the shell, through which channels I 
gas could pass without meeting the wash-water. 

The material most commonly employed in washers is 
coke in pieces of from 2 1 j to 3K inches in size. This 
material is cheap and is very well suited for retaining 



the impurities of the gas. The largest pieces of coke 
should be placed at the bottom of the washer, and 
smaller pieces should form at the top a layer from 6 to 

8 inches deep. In this manner I he water it distributed 
more evenly and the gai in more thoroughly washed. 
Blast-furnace coke is best suited for this washing, (U it 
is more porous and less brittle than gas-works coke. It 


put a baffle-board in front of the 

gas out- 

let to reduce the carrying along of water in the con- 

The tower of the washer should be provided with 
three openings having air-tight closures, easily fastened 
by screws (Fig. 129). One of the openings is located 
in the lower compartment, slightly above the water 
level, to allow the deposits to be removed and to per- 
mit the cleaning of the orifice of the gas-supply tube, 
which is particularly liable to be obstructed. The sec- 
ond opening is placed above the grating which sup- 
ports the filtering material. The third opening is pro- 
vided on the top of the apparatus to permit the exam- 
ination and cleaning of the water feed device and the 
gas outlet without the necessity of taking the lid of the 
washer apart, the joint of which is kept tight with diffi- 
culty. The two openings last mentioned also serve for 
introducing and removing the filtering material. 

Purifying Apparatus. — In some cases, where it is 
necessary to have very clean gas or where coal is em- 
ployed which is softer than anthracite coal, and which 
therefore produces an appreciable amount of tar, sup- 
plementary purifying means must be employed. The 
apparatus for this purpose may, like the washers, be 
based upon a physical action or upon a chemical action. 
The physical action has for its purpose chiefly to re- 
tain the pitch and the dust which may have passed 
through the washer. 

This is accomplished by means of sawdust or wood 
shavings arranged in a thin layer and capable of filter- 



ing the gas without opposing too great a resistance to 
its passage. These materials are spread on one or more 
shelves superposed to form successive compartments in 
a box closed in an air-tight manner by an ordinary lid 
or a water seal cover (Pintsch, Fig. 130; Fichet and 
Heurtey, Fig. 131)- It may be well to point out that 
the presence of the water carried along will, in the end, 
destroy the efficiency of the precipitated materials, 

because they swell up and cease to be permeable to 
the gas. These materials must therefore be renewed 
rather frequently. To obviate this drawback, vegetable 
moss may be employed, which is much less affected by 
moisture than most filters and keeps its spongy condi- 
tion for a long time. 

The chemical action has for its chief object to rid 
the gas of the carbonic acid and the hydrogen sulphide 
which certain fuels give off in appreciable amounts. 

2 4 6 

The purifying material, in this case, is formed cither 
by a mixture of hydrate of lime and natural iron oxide, 
or by the so-called Laming mass, which consists of iron 
sulphide, slaked lime, and sawdust, which last serves 

the purpose of rendering the material looser and i 
permeable to the gas. The Laming mass as well as 
other purifying materials will become exhausted in the 
course of chemical reactions. It can be regenerated 
merely by exposure to the air. 



Gas-Holders. — The purifiers by themselves consti- 
tute, to a certain extent, storage chambers for the gas 
before it is supplied to the engine ; but in plants for thu 
generation of gas without purifiers it is advisable to 
provide a gas-holder on the suction conduit near the 

In order to save floor space the gas-holder may be 


Pi&tSCb ri'Kulaling-ijdl. 

placed in the basement. Preferably the capacity of 
the holder should be at least from 3 to 4 times the vol- 
ume of the engine-cylinder. The holder should also 
be provided with a drain-cock and with a hand-hole 
located at some accessible point, so that the slimes and 
pitch which tend to accumulate in the holder can be 
removed. In some cases the gas-holder is formed by a 

small regulating bell, the function of which is to in- 
sure a uniform pressure. This bell is emptied during 
the suction period and is filled during the three suc- 

Fic- 133.— Types cif gas-di 

ceeding periods of compression, explosion, and exhaust 
(Pintsch, Fig. 132). 

Drier. — Sometimes, toward the end of a producer- 
gas pipe, a drier is located for the purpose of keeping 
back the water carried along, the drier being similar to 
that employed in steam conduits. It will, of course, be 

understood that such driers are useful only in plants 
having no purifiers (Fig. 133). The employment of 
the drier is advisable to prevent the entrance of moist 
gas into the cylinder and the condensation of moisture 
on the electric igniter, 
Pipes. — The pipes connecting the several parts of 




a gas-producing plant should be disposed with pMtic- 
ular care to insure tightness and cleanliness. It should 
be borne in mind that the gas is under a pressure below 
that of the atmosphere, and that the least leakage will 
cause the entrance of air, which will impair the qual- 
ity hi the gas. The greatest care should therefore be 
taken in fitting the joints. These joints are numerous, 
because there are joints wherever tubes are connected 
with each other and with the apparatus. Further- 
more, all elbows should be provided with covers held 
m place by a yoke and compression screw, this being 
done for the purpose of providing for the introduction 
of a brush or other implement to remove the dust and 
pitch (Fig. 134). 

For conduits of small diameter the elbows with cov- 
ers may be replaced with T connections, or connections 
provided with plugs. 

Gas piping in the immediate neighborhood 01 the 
cock for admitting gas to the motor should he provided 
with a conduit of proper diameter leading to the open 
air and serving to clean the apparatus and to fill them, 
during the operation of the fan, with gas suitable for 
combustion. This conduit should be provided with a 
stop-cock. Test-cocks for the gas should be placed on 
the piping immediately beyond the vaporizers, the 
scrubber, and near the engine. 

It will also be well to provide water-pressure gages 
before and after the scrubber to enable the attendant 
to ascertain the vacuum in the conduits and to adjust 
the running of the apparatus. 


Purifying-Brush. — As an additional precaution 
against the carrying of tar to the engine, metallic 
brushes are often employed, these brushes being spiral 
in form and enclosed in a cast-iron box interposed in 
the gas-supply pipe immediately after the engine. The 

Fig. 135.— -Metal purifying-brush. 

gas will be broken up into streams by the obstacles 
formed by these brushes and will be freed of the sus- 
pended tar (Fig. 135). These brushes should be care- 
fully cleaned at regular intervals. The best way of 
doing this is to drop them into kerosene or some other 
suitable solvent. 



These conditions depend upon the workmanship or 
upon the system of the plant, on the care with which 
it has been erected, on the nature of the fuel, on 
the condition of preservation of the apparatus, and 
upon the manner in which the producers have been 

Workmanship and System.— The workmanship 
itself, which term is meant to include the choice of 
materials and the way they have been worked, presents 
no difficulty. The producers which we have discussed 
are very simple and offer absolutely no difficulties in 
their mechanical execution. As regards the system, 
however, especially with respect to the relative dimen- 
sions of the elements, it does not seem so far that it is 
possible to indicate any principle or rule capable of 
a rigid general application. It must be taken into, 
account that the use of suction gas-generators has 
become general only in the last three or four years; 
the problem has therefore scarcely been adequately 
solved. However, some hints may be given on this 

Generator.— In regard to the generator, it is pos- 
sible to deduce from the best existing plants the dimen- 
sions to be given to the generator relatively to those of 
the engine to be supplied, upon the assumption that the 
engine is single-acting and runs at a normal speed of 


from 1 60 to 230 revolutions per minute. The essential 
portion of the generator which contributes to the pro- 
duction of a proper gas is that which corresponds with 
the combustion zone. To this portion a cross-section is 
given varying in size between one-half and one-quarter 
of the surface of the engine-piston, sometimes between 
one-half and nine-tenths of this surface, according to 
the nature and the size of the fuel that is used. With 
small apparatus, however, ranging from 5 to 15 horse- 
power, the size of the base cannot be reduced below a 
certain limit, since otherwise the sinking of the fuel 
will be prevented. This danger always exists in small 
generators and renders their operation rather uncertain, 
such uncertainty being also due to the influence of the 
walls. It is to be noted that most modern generators are 
rather too large than otherwise. 

Many manufacturers of no wide experience have 
been led to make their apparatus rather large so as to 
insure a more plentiful production of gas. As a matter 
of fact, the fire in such apparatus is liable to be extin- 
guished when the combustion is not very active. If the 
principles of the formation of gas in suction-generators 
be kept in mind, it is evident that the gas developed is 
the richer the " hotter " the operation of the apparatus. 
Such operation also permits the decomposition of the 
hydrogen and carbon monoxide. 

The " hot " operation of a generator is accomplished 
best with active combustion ; and since this is a function 
of the rapidity with which the air is fed, it obviously is 
advantageous to reduce the area of the air-passage to a 


2 53 


minimum as far as allowed by the amount of fuel to be 
treated. As to the height of the fuel in use in the ap- 
paratus, this varies as a rule between 4 and 5 times the 
diameter at the base. 

Vaporizer. — The size of the vaporizer varies ma- 
terially according to its type- No hard-and-fast rule 
can therefore be adopted for determining its heating 
surface ; but this surface should in all cases be sufficient 
to vaporize under atmospheric pressure from .66 to .83 
pounds of water per pound of anthracite coal consumed 
in the generator. 

Scrubber. — For the scrubbers, the following dimen- 
sions may be deduced from constructions now used by 
standard manufacturers. 

The volume of a scrubber is generally from six to 
eight times the anthracite capacity of the generator. A 
height of from three to four times the diameter is con- 
sidered sufficient in most cases. It should be under* 
stood that in this height is included the water-pan 
chamber located below the partition or grate, and the 
upper chamber through which the gas escapes. The 
height of these two chambers depends necessarily upon 
the arrangement used for leading the gas to the lower 
portion of the washer and for the distribution of wash- 
water at the top. 

Assembling the Plant.— The author has insisted 
strongly on the necessity of having all the apparatus 
and pipe connections perfectly tight. In order to as- 
certain if there is any leakage, the following procedure 
may be adopted: 



When starting the fire by means of wood, straw, or 
other fuel producing smoke, instead of allowing this 
smoke to escape through the flue during the operation 
of the fan, it may be caused to escape through the cock 
which generally admits the gas to the motor, the cock 
being opened for this purpose. The damper in the out- 
let flue is closed. In this manner the smoke will fill all 
the apparatus and connecting pipes under a certain 
pressure and will escape through any cracks, the pres- 
ence of which will thus be revealed. 

Another test, which is made during the ordinary op- 
eration of the generator, consists in passing a lighted 
candle along the joints; if there is any leakage, this will 
be shown by a deviation of the flame from a vertical 

Fuel. — We have discussed the subject of fuel in a 
preceding chapter (Chapter XIII) and have indicated 
the conditions to be fulfilled by low grade or anthracite 
coal best adapted for use in suction gas-generators. It 
may here be added that the coal used in the generator 
should be as dry as possible and in pieces of from 
Vx inch to 1 inch. Very small pieces, and particularly 
coal dust, are injurious and should be removed by pre- 
liminary screening as far as possible. Screened coal 
is thrown in with an ordinary grate shovel. 

How to Keep the Plant in Good Condition.— In 
regard to the generator, apart from the cleaning of the 
grate and of the ash-pit, which may be done during 
operation, it is necessary to empty the apparatus en- 
tirely once a week, if possible, in order to break off the 



in ci 


clinkers adhering to the retort. These clinkers destroy 
the refractory lining, form rough projections interfer- 
ing with the downward movement of the fuel, bring 
about the formation of arches, and reduce the effective 
area of the retort. At the time of this cleaning, testa 
are also made as to the tightness of the doors of the 
combustion-chamber, of the charging-boxes, etc. 

The vaporizer should be cleaned every week or every 
other week, according to the more or less bituminous 
character of the fuel and the greater or smaller content 
of lime in the water used. Lime deposits may be 
eliminated, or the salts may be precipitated in the form 
of non-adhering slimes, by introducing regularly a 
small amount of caustic postash or soda into the feed- 
water. If the deposits or incrustations are very tena- 
cious, the use of a dilute solution of hydrochloric acid 
may be resorted to. Tar which may adhere to the 
conduits, pipes or gas passages, is best removed while 
the apparatus is still hot, or a solvent may be employed, 
such as kerosene, turpentine, etc. The connections be- 
tween the vaporizer and the scrubber are particularly 
liable to become obstructed by the accumulation of tar 
or dust carried along by the gas. 

It is advisable to examine the several parts of the 
plant once or twice a week by opening the covers or the 

The lower compartment of the washer keeps back 
the greater part of the dust which has not been retained 
in collectors or boxes provided especially for this pur- 
pose. The dust takes the form of slime, and, in some 


arrangements of apparatus, tends to clog up the over- 
flow pipe, thus arresting the passage of gas and causing 
the engine to stop. This portion of the washer should 
be thoroughly cleaned once or twice a month. 

If very hard blast-furnace coke is used in the washer, 
it may be kept in use for over a year without requiring 
removal. In order to free the purifying materials from 
dust and lime sediments carried along by the wash- 
water, it is well to let the wash-water flow as abundantly 
as possible for about a half-hour at least once a month. 
At the time of renewing the purifying material the 
precautions indicated in the section dealing with these 
matters should be observed, and care should be taken 
to have shelves or gratings on which the material is 
supported in layers not too thick, so as to avoid any 
resistance to the passage of the gas. 

In a general way it is advisable to test the drain- 
cocks on the several apparatus daily, and to keep them 
in perfect condition. If, when open, one of these cocks 
does not discharge any gas, water, or steam, a wire 
should be introduced into the bore to make sure it is 
not clogged up. 

Care of the Apparatus.— Each producer-gas plant 
will require special instructions for running it, accord- 
ing to the system, the construction, and the size of the 
plant. Such instructions are generally furnished by 
the manufacturer. However, there are some general 
rules which are common to the majority of suction gas- 
producers, and these will here be enumerated. 

Starting the Fire for the Gas Generator. — This 



operation calls for the presence of the engineer of the 
plant and an assistant. The proper procedure is as fol- 
lows : 

First: Open the doors of the furnace and of the ash- 
pit. Then open the outlet Hue and make sure that the 
grate of the generator is clear of ashes and clinkers. It 
should also be seen to that the parts of the charging-box 
work well and that the joints are tight. 

Second : Ascertain whether there is the proper 
amount of water in the vaporizer, in the scrubber, etc., 
and that the feed works properly. 

Third: Through the door of the combustion-cham- 
ber introduce straw, wood shavings, cotton waste, etc.; 
light them and fill the generator with dry wood up to 
one-quarter or one-half of its height; then add 1 few 
pailfuls of coal. 

Fourth: Close the doors of the ash-pit and of the 
combustion-chamber and start the draft by means ni the 
fan. As soon as the draft is started, it must be kept up 
without interruption until the engine begins tu run, 
which may be ten or twenty minutes after lighting 
the fire. 

Fifth; After the draft has been continued for l few 
minutes, the coal becomes sufficiently incandescent to 
start the production of gas, which may be ascertained 
by trying to light the gas at the test-cock near the gen- 
erator. Then the opening in the outlet flue is half 
closed for the purpose of producing pressure in the 

Sixth : Open the outlet Hue adjacent to the engine for 


the purpose of purging the apparatus and the conduits 
of the air which they contain until the gas may be 
lighted at the test-cock placed near the motor. 

Seventh: Adjust the normal outflow of wash-water 
for the scrubber. 

Eighth : As soon as the gas burns continuously at the 
test-cock with an orange-colored flame the engine may 
be started. 

The gas at first burns with a blue flame; this color 
indicates that it contains a certain amount of air. The 
opening of the test-cock should be so regulated as to 
reduce the outlet pressure of the gas sufficiently to pre- 
vent the flame from going out. During the production 
of the draft, as well as during the ordinary running of 
the plant, the filling of the apparatus with fuel should 
be done with care to prevent explosions of gas due to the 
entrance of air. Particular care should be taken never 
to open at the same time the lid of the charging-box and 
the device, be it a cock, valve, or damper, which con- 
trols the connection of the charging-box with the gen- 
erator. All the operations which have been mentioned 
above should be carried out as quickly as possible. 


The manner of starting the engine depends on the 
type of the engine and on the starting device with 
which it is provided, as wc have already explained in 
connection with engines working with gas from city 




It is, however, important for the production of a 
good explosive mixture to regulate the amount of air 
supplied to the engine according to the quality of the 
gas employed. It is advisable to continue the operation 
of the fan until several explosions have taken place in 
the cylinder and the engine has acquired a certain 
speed so as to be able to draw in the normal amount 
of gas. 

Naturally the gas-outlet tube near the admission- 
cock should be closed after starting the engine, as 
well as the opening in the outlet flue of the generator. 
When the motor is running properly, the amount of 
water fed to the vaporizer and overflowing to the ash- 
pit is properly adjusted. The generator is then filled 
up to the level indicated by the manufacturer. 

Care of the Generator during Operation. — As 
soon as the apparatus is running under normal con- 
ditions, it presents the advantage of requiring only very 
slight supervision and very little manual tending. The 
supervision consists: 

First: In regulating and keeping up a proper feed 
of water to the vaporizer. 

Second: In seeing to it that in apparatus provided 
with an overflow leading to the ash-pit, the water 
should flow constantly but without exceeding the 
proper amount. 

Third: In keeping down temperature in the scrub- 
ber by properly regulating the feed of the wash-water. 
This apparatus may be slightly warm at its lower part, 
but must be quite cold at the top. 


The manual tending to be done is limited to the reg- 
ular filling up of the generator with fuel and to the 
removal of ashes and clinkers. The charging is effected 
at regular intervals, which, according to the various 
types of anthracite-generators, vary from one to six 
hours. Charging the apparatus at short intervals en- 
tails unnecessary labor, while charging at too long 
intervals will often interfere with the uniform produc- 
tion of the gas. 

It will be obvious that the amount of fuel introduced 
will be the larger, the greater the intervals between two 
fillings. This fuel is cold and contains between its 
particles a certain amount of air; furthermore, the layer 
of coal which covers the incandescent zone has become 
relatively thin. The excess of air impoverishes the gas, 
and the fresh fuel lowers the temperature of the mass 
undergoing combustion, so that again the gas in process 
of formation is weakened. Experience seems to show 
that as a rule it is best to fill up the generator at inter- 
vals of from two to three hours, according to the work 
done by the engine. It should be noted that the level 
of the fuel in the generator should not sink beluw the 
bottom of the feed-hopper. 

The author wishes again to emphasize that in order 
to prevent the harmful entrance of air, the charging 
operations should be carried out as quickly as possible ; 
and for this reason the fuel should be introduced not by 
means of the shovel, but by means of a pail, scuttle, or 
other appropriate receptacle. 

Care should be taken to fill the charging box to its 



upper edge and to adjust its cover accurately before 
operating the device which closes the feed-hopper 
(valve, cock). 

The removal of the ashes and clinkers should be ac- 
complished as infrequently as possible, since opening 
the doors of the ash-pit and of the combustion-chamber 
necessarily causes an inward suction of cold air which 
is harmful. 

As a rule with generators employing anthracite coal, 
it is sufficient to empty the ash-pit twice daily; this 
should be preferably done during stoppages. How- 
ever, the cleaning of the grate by means of a poker 
passed between the grate-bars or over them in order 
to bring about the falling of the ashes, should be at- 
tended to every two to four hours, according to the type 
of the generator and the nature of the fuel. In order 
that this cleaning may be done without opening the 
doors, the latter should be provided with apertures hav- 
ing closing devices. 

This cleaning has for its chief object to allow the free 
passage of the air for supporting combustion and to 
keep the incandescent zone in the apparatus at the 
proper height. The accumulation of ashes and clinkers 
at the bottom of the retort will shift this zone upward 
and impair the quality of gas. 

Stoppages and Cleaning.-After closing the gas- 
inlet to the engine, the damper in the gas-outlet flue 
' the generator should be opened and the cocks con- 
oiling the feed of water to the scrubber and to the 
vaporizer should be closed. 



If it is desired to keep up the fire of the generator 
during the stoppage so as to be able to start again 
quickly, the ash-pit door should be opened so as to pro- 
duce a natural draft which will maintain combus- 
tion. While the door is open, the clinkers which bare 
accumulated above the grate may be removed, as they 
are much more easily taken off the grate when they 
are hot. 

At least once a week the fire in the generator should 
be put out and the generator completely cleaned — that 
is, when ordinary fuel is employed. For this purpose, 
as soon as the apparatus is stopped, a portion of the in- 
candescent fuel is withdrawn through the doors of the 
combustion-chamber, and the retort is allowed to cool 
before it is emptied entirely. Too sudden a cooling of 
the retort may injure its refractory lining. In order 
to prevent explosions caused by the entrance of air, the 
feed-hopper should remain hermetically closed during 
the removal of the incandescent fuel through the doors 
of the combustion-chamber. 

If the apparatus is placed in a room poorly venti- 
lated, the cleaning should be attended to by two men, 
so that one may assist the other in case he is overcome 
by the gas. In all cases there should be a strict prohibi- 
tion against the use of any light having an exposed 
flame liable to set on fire the explosive mixtures which 
may be formed. 

When the generator, after cooling, is completely 
■open, the charging-box is taken apart, and, if necessary, 
the feed-hopper also; the grates are taken out, if neces- 


sary ; and, by means of a poker inserted from above, the 
clinkers and slag adhering to the retort are broken 

In the foregoing paragraphs the author has indicated 
how the several apparatus, such as the vaporizer, the 
washer, the conduits, etc., should be attended to and 
maintained in good working order. 



Although this book is devoted primarily to a dis- 
cussion of street-gas and producer-gas engines em- 
ployed in various industries, a few words on oil and 
volatile hydrocarbon engines may not be out of place. 

Oil-engines are those which use ordinary petroleum 
as a fuel or illuminating oil of yellowish color, having 
a specific gravity varying from 0.800 to 0.820 at a tem- 
perature of 15 degrees C. (490 degrees F.), and boiling 
between 140 and 145 degrees C. (284 to 297 degrees 
F.). Volatile hydrocarbon engines are those which 
employ light oils obtained by distilling petroleum. 
These oils are colorless, have a specific gravity that 
varies from 0.680 to 0.720, and boil between 80 degrees 
and 115 degrees C. (176 to 257 degrees F.). Among 
these " essences," as they are called in Europe, may be 
mentioned benzine and alcohol. 

In general appearance, and the way in which they 
are controlled, oil-engines differ but little from gas- 
engines. Their usual speed, however, is 20 to 30 per 
cent, greater than that of gas-engines. Except in some 
engines of the Diesel and Banki types, the compression 
does not exceed 43 to 71 pounds per square inch. In 
volatile hydrocarbon engines, on the other hand, the 
speed is very high, often running from 500 to 2,000 



revolutions per minute, while the speed of gas or oil 
engines rarely exceeds 250 or 300 revolutions per 

Oil -Engines. — Oil-engines are employed chiefly in 
Russia and in America. Because of the high price of 
oil in other countries they are to be found only in small 
installations in country regions and are used mainly 
for driving locomobiles and launches. The improve- 
ments which have been made of late years in the con- 
struction of gas-engines supplied by suction gas-pro- 
ducers for small as well as for large powers, have hin- 
dered the general introduction of oil-engines. 

The characteristic feature in the design of many of 
the oil-engines of the four-cycle type now in use (to 
which type we shall confine this discussion) is to be 
found in the controlling mechanism employed. The 
underlying principle of this mechanism lies not in acting 
upon the admission-valve, but in causing the governor 
to operate the exhaust-valve in such a manner that it 
is held open whenever the engine tends to exceed its 
normal speed. Some engines, however, are built on the 
principle of the gas-engine, with an admission-valve so 
controlled by the governor that it is open during nor- 
mal operation and closed whenever the speed becomes 

The necessity of producing a mixture of air and oil 
capable of being ignited in the engine-cylinder has 
led to the invention of various contrivances, which 
cannot be used if illuminating-gas or producer-gas be 
employed. These contrivances are the atomizer, the 


carbureter, the oil-pump, the air-pump, the oil-tank, 
and the oil-lamp. In some oil-engines all of the ele- 
ments may be found, but for the purpose of simplifying 
the construction and of avoiding unnecessary complica- 
tions, manufacturers devised arrangements which ren- 
dered it possible to discard some of them, particularly 
those of delicate construction and operation. It is 
not the intention of the author to enter into a detailed 
description of these various devices, since the limita- 
tions of this book would be considerably surpassed. The 
reader is referred to books on the oil-engine, published 
in the United States, England, and France.* 

Most of the observations which have been made on 
the construction and installation of gas-engines, as well 
as the precautions which have been advised in the con- 
duct of an engine, apply with equal force to oil-engines. 
It will therefore be unnecessary to recur to this phase 
of the subject so far as oil-engines are concerned. One 
point only should be insisted upon — the necessity of 
very frequently cleaning the valves and moving parts 
of the engine. 

Illuminating-oil when burnt produces sooty deposits, 
particularly if combustion be incomplete, which de- 
posits foul the various parts and cause premature igni- 
tions and faulty operation. 

"Hiscox, Gas and Oil Engines, Norman W. Henley Pub. Co., New- 
York. Parse!! and Weed, Gas and Oil Engines, 1900, Norman W. 
Henley Tub. Co., New York. Goldingham, 1900, Span & Cbamberlain. 
London. Uugald Clerk, 1897, Longmans, London. Grover, iqoz, Hey- 
wood, Manclusler. Aime Witz, 1904, Barnard, Paris. H. Giildner, 1903, 
Springer. Berlin. 


The use of oil in atomizers, carbureters, and lamps 
is accompanied with the employment of pipes and open- 
ings so small in cross-section that the slightest negligence 
is attended with the formation of partial obstructions 
that inevitably affect the operation of the engine. 

Volatile Hydrocarbon Engines. —Only those en- 
gines will here be treated which have become of im- 
portance in the development of the automobile. 

Some designers have attempted to employ the vola- 
tile hydrocarbon engine for industrial and agricultural 
purposes, and have devised electro-generator groups, 
hydraulic groups, and so-called " industrial combina- 
tions " in which belt and pulley transmission is em- 
ployed. These applications in particular will here be 
rapidly reviewed. 

The high speed at which engines of this class are 
driven renders it possible to operate a centrifugal pump 
directly and to mount both the engine and machine 
which it actuates on the same base. The hydrocarbon 
engine has the merit of being very light and of taking 
up but little room. Its cost is considerably less than 
that of an oil or producer-gas engine of corresponding 
power. On the other hand, its maintenance is much 
more expensive, and the hydrocarbons upon which it 
depends for fuel anything but cheap. Furthermore, 
the engines wear away rapidly, on account of their high 
speed. For this reason it is advisable to base calcula- 
tions on a life of three to four years, while oil and gas 
engines may generally be considered to be still of ser- 
vice at the end of thirteen years. On the following 


page a t 

mparison of costs for installation and main- 
s drawn between the oil and hydrocarbon 
engine on the basis of ten horse-power. 

Comparative Costs. — A 10 horse-power oil-engine, 
in the matter of first cost of installation, is about 35 
per cent, more expensive than a volatile hydrocarbon 
engine of equal power, On the other hand, the operat- 
ing expenses of the oil-engine are less by 25 per cent, 
than they are for the volatile hydrocarbon engine. 

The engines which arc here discussed usually have 
their cylinders vertically arranged, as in steam-engines 
of the overhead cylinder type. The crank-shaft and 
the connecting-rods are enclosed in a hermetically 
sealed box filled with oil, so that the movement of the 
parts themselves ensures the liberal lubrication of the 
piston. The suction-valve is generally free, although 
latterly designers have shown a tendency to connect 
it with the cam-shaft, with the result that it has become 
possible to reduce the speed appreciably without stop- 
ping the engine. The carbureter is operated by the 
suction of the engine. If the fuel employed is alcohol, 
it must be heated. 

Tests of High-speed Engines.— High-speed engines 
present various difficulties which must be contended 
with in controlling their operation, Their high speed 
renders it impossible to take indicator records as in the 
case of most industrial engines. Indicator cards, more- 
over, at best give but very crude data, which relate to 
each explosion cycle only, and which are therefore in- 
adequate in determining the exact conditions of an en- 



gine's operation. Oil, benzine, and other so-called car- 
bureted-air engines are particularly difficult to control 
because of many phenomena which cannot be recorded. 
In order to test the operation of high-speed engines, 
two different types of instruments are at present em- 
ployed: the manograph and the continuous explosion 

The Manograph. — The manograph, which is the 
invention of Hospitalier, is an optical instrument in 
which a series of closed diagrams are superimposed 
upon a polished mirror similar in form to Watt 
diagrams. Because the images persist in affecting the 
retina of the eye an absolutely continuous, but tem- 
porary, gleam is seen. Still, it is possible to obtain a 
photograph or a tracing of these diagrams. 

The Continuous Explosion Recorder for High- 
speed Engines. — The author has devised an explo- 
sion and pressure recorder, which is mounted upon the 
explosion chamber to be tested and which communi- 
cates with the chamber through the medium of a 
cockr {Fig. 136). The instrument is somewhat similar 
in form to the ordinary indicator. Its record, however, 
is made on a paper tape which is continuously un- 
wound. The cylinder r is provided with a piston p, 
about the stem of which a spring s is coiled. A clock 
train contained in the chamber b unwinds the strip of 
paper from the roll />' and draws it over the drum p\ 
where the pencil t leaves its mark. The tape is then 
rewound on the spindle p'". A small stylus or pencil f 
traces " the atmospheric line " on the paper as it passes 


over the drum p". In order to obviate the binding of 
the piston p when subjected to the high temperature of 

R. Mat hot's continuous explosion recorder. 

the explosions, the cylinder c is provided with a casing 
e in which wat;r is circulated by means of a small rub- 
ber tube which fits over the nipple e . This recorder 


analyzes with absolute precision the work of all en- 
gines, whatever may be their speed. It gives a con- 
tinuous graphic record from which the number of ex- 
plosions, together with the initial pressure of each, can 
be determined, and the order of their succession. Con- 
sequently the regularity or irregularity of the variations 
can be observed and traced to the secondary influences 
producing them, such as the section of the inlet and out- 
let valves and the sensitiveness of the governor. It 
renders it possible to estimate the resistance to suction 
and the back pressure due to expelling the burnt gases, 
the chief causes of loss in efficiency in high-speed en- 
gines. Furthermore, the influence of compression is 
markedly shown from the diagram obtained. 

The recorder is mounted da the engine; its piston is 
driven back by each of the explosions to a height cor- 
responding with their force; and the stylus or pencil 
controlled by the lever / records them side by side on 
the moving strip of paper. The speed with which this 
strip is unwound conforms with the number of revolu- 
tions of the engine to be tested, so that the records 
of the explosions are placed side by side clearly and 
legibly. Their succession indicates not only the num- 
ber of explosions and of revolutions which occur in 
a given time, but also their regularity, the number 
of misfires. The atmospheric pressure of the explo- 
sions is measured by a scale connected with the re- 
corder-spring. By employing a very weak spring 
which flexes at the bottom simply by the effect of 
the compression in the engine-cylinder, it is possible 


to ascertain the amount of the resistance to suction and 
to the exhaust. It is simply sufficient to compare the 
explosion record with the atmospheric line, traced by 
the stylus /. By means of this apparatus, and of the 
records which it furnishes, it is possible analytically to 
regulate the work of an engine, to ascertain the propor- 
tion of air, gas, or hydrocarbon, which produces the 
most powerful explosion, to regulate the compression, 
the speed, the time of ignition, the temperature, and the 
like (Figs. 137, 138 and 139). 

In order to explain the manner of using this recorder 
several specimen diagrams are here given. 

I. Determination of the Amount of Compression. — 
A spring of average power is employed, the total flexion 
of which corresponds almost with the maximum com- 
pression so as to obtain a curve of considerable ampli- 
tude. The engine is first revolved without producing 
explosions, driving it from the dynamo usually em- 
ployed in shops, at the different speeds to be studied. 
The compression of the mixture varies in inverse ratio 
to the number of revolutions of the shaft, owing to the 
resistances which are set up in the pipes and the valves 
and which increase with the speed. The accompany- 
ing cut (Fig. 140) shows two distinct records taken in 
two different cases, namely: 

A. — Speed of engine, 950 revolutions per minute; 
amount of compression, 68.9 pounds per square inch. 

B. — Speed of engine, 1,500 revolutions per minute; 
amount of compression, 61 pounds per square inch, or 
1 1.5 per cent. less. 


II. Determination of the Resistance to Suction 
Exhaust. — Influence of the tension of the spring of the 
suction valve and of the section of the pipe. Effect of 


the section of the exhaust-valve and of the length and 
shape of the exhaust-pipe: 

A very light spring is utilized, the travel of which is 
limited by a stop so as to obtain on a comparatively 
large scale the depressions and resistance respectively 
represented by the position of the corresponding curve, 
above or below the atmospheric line (Fig. 141). 

1 „ — . 

Fie. 141. 

C. — Tension of the suction-valve: 2.9 pounds. Re- 
sistance to suction: \ of an atmosphere (2.7 pounds). 

D.— Tension of the suction-valve : 2. 1 7 pounds. Re- 
sistance to suction: f of an atmosphere (5.4 pounds). 

E. — A chest is used for the exhaust. Resistance to 
exhaust: I of an atmosphere (5.4 pounds). 

F.— The exhausted gases are discharged into the air, 




the pipe and the chest being discarded. Resistance to 
the exhaust is zero (Fig. 142). 

The depression graphically recorded is partly due 
to the inertia of the spring of the explosion-recorder, 

which spring expands suddenly when the exhaust is 

III. Comparison of the Average Force of the Ex- 
plosions by Means of Ordinates. — A powerful spring is 
employed. The paper band or tape of the recorder 
is moved with a small velocity of translation so as to 
approximate as closely as possible the corresponding 
ordinates representing the explosions (Fig. 143). 

I kdflfltt 

Fig. 143. 

G. — Pure alcohol. Explosive force, 369.72 to 426.6 
pounds per square inch. 

H. — Carbureted alcohol. Explosive force, 397.6 to 
510.8 pounds per square inch. 

I. — Volatile hydrocarbon. Explosive force, 483.48 
to 531.92 pounds per square inch. 


IV. Analysis of a Cycle by Means of Open Diagrams 
Representing the Four Periods.— A powerful spring is 
employed, and the paper is moved with its maximum 
speed of translation. The four phases of the cycle are 
easily distinguished as they succeed one another graph- 
ically from right to left — in other words, in a direction 
opposite to that in which the paper is unwound. A 
diagram is made which reproduces exactly the values 
of the corresponding pressures at different points in the 
travel of the piston (Fig. 144). The periods of the 


cycle are reproduced as faithfully as if the ordinary in- 
dicator which gives a closed curved diagram had been 
employed. There is no difficulty in reading the record, 
since the paper is not in any way connected with the 
engine-piston. Some attempts have been made to secure 
open diagrams in which the motion of translation given 
to the paper is controlled by the engine itself; but these 
apparatus as well as the ordinary indicators cannot be 
used when the speed of the engine exceeds 400 to 500 
revolutions per minute. 

J. — Speed, 1,200 revolutions; carbureted alcohol; 
average force of the explosions, 426.6 pounds per 
square inch. Average compression, 92.43 pounds per 
square inch. Pressure at the end of the expansion, 
21.33 pounds per square inch. 


V. Analysis of the Inertia of the Recorder. Selection 
of the Spring to be Employed. — Given the rapidity 
with which the explosions succeed one another in auto- 
mobile engines, it is readily understood that the inertia 
of the moving parts of the recorder will be graphically 
reproduced (Fig. 144). The effect of this inertia is a 
function of the weight of the moving parts and of the 
extent of their travel. 

The moving masses are represented by the piston and 
its rod, the spring and the levers of the parallelogram 
stylus. The effects due to inertia have been consider- 
ably lessened by reducing the weight of the various 
parts to a minimum. A hollowed piston, a hollowed 
rod and short and light levers have been adopted. The 
traditional pencil has been displaced by a silver point 
which traces its mark upon a metallically coated paper. 
For the heavy springs with their long travel, light but 
powerful springs with small amplitudes have been sub- 
stituted. Since the perfect lubrication of the recorder- 
cylinder is of great importance, a simple oiling device 
certain in its action has been adopted. The recess of the 
piston forms a cup that can be filled with oil whenever 
the spring is changed. 

At each explosion the violent return of the piston 
splashes oil against the cylinder walls and thus insures 
perfect lubrication. It should be observed that if the 
directions given are not followed, particularly in the 
choice of a spring suitable for each experiment, inertia 
effects will be produced. These can easily be detected 
on the record and cannot be confused with the curves 


which interpret the phenomena occurring in the cyl- 
inder of the engine. At a height equal to the end 
of the piston's stroke, the cylinder of the recorder is 
provided with a water-jacket which keeps the tempera- 
ture down to a proper point and prevents the binding of 
the piston. 

The explosion-chamber of automobile engines being 
rather small in volume, should not be sensibly increased 
in order that the record obtained may conform as nearly 
as possible with actual working conditions on the road. 
In order to attain this end the cylinder of the recorder 
is so disposed that the piston travels to the height of the 
connecting-cock. As a result of this arrangement the 
field of action of the gases is reduced to a minimum. 
Since these gases have no winding path to follow, they 
are subjected neither to loss of quantity nor to cold. 



THE conditions which must be fulfilled both by en- 
gines and gas-producers in order that they may in- 
dustrially operate with regularity and economy have 
been dwelt upon at some length. Unfortunately it often 
happens that engines are not installed as they should be, 
with the result that they run badly and that the reputa- 
tion of gas-engines suffers unjustly. The use of suction 
gas-producers in particular caused considerable trouble 
at first owing to inexperience, so that even now many 
hesitate to adopt them despite their great economical 
advantages. The reason assigned for this hesitation is 
the supposed danger attending their operation. 

The factory proprietor who intends to install a gas- 
engine in his plant is not usually able to appreciate the 
intrinsic value of one engine when compared with an- 
other, or to determine whether the plans for an installa- 
tion conform with the best practice. The innumerable 
types of engines offered to him by manufacturers and 
their agents, each of whom claims to have a better en- 
gine than his rivals, plunges the purchaser into hesita- 
tion and doubt. Not knowing which engine to select, he 
usually buys the cheapest. .Very often he learns, as time 

goes by, that his installation is far from being perfect. 

279 1 


Finally he begins to believe that he ought to consult an 
expert. The author's personal experience has con- 
vinced him that eight times out of ten the factory owner 
who has picked out an engine for himself has not ob- 
tained an installation which meets the requirements 
which the manufacturers of gas-engines should fulfil. 
Many of these requirements could be complied with 
were it not for the fact that the manufacturer has 
dropped certain details which appeared superfluous, 
but which were in reality very important in obtaining 
perfect operation. The author therefore suggests that 
the services of a competent expert be retained by those 
who intend to install a gas-engine in their plants. 

The Duty of a Consulting Engineer.— An expert 
fills the same office as an architect, and impartially 
selects the engine best suited to his client's peculiar 
needs. His examination of the engines offered to him 
will proceed somewhat according to the following pro- 
gramme : 

i. He will first study the installation from the 
mechanical point of view, and also the local conditions 
under which that installation is to operate, in order that 
he may not order an engine too large or too small, or 
a type incompatible with the foundations at his dis- 
posal, or unable to fulfil all the requirements of his 

2. He will examine the precautions which have been 
taken to avoid or reduce to a minimum certain incon- 
veniences which attend the operation of explosion- 

3. He wil 


He will draw up specifications, with the terms 
of which gas-engine makers must comply, so that he can 
compare on the basis of these specifications the merits 
of the engines submitted to him. 

4. He will prepare an estimate of cost and also a 
contract which is not couched in terms altogether in the 
gas-engine maker's favor, and which gives the pur- 
chaser important warranties. 

5. He will supervise the technical installation of the 
engine or plant. 

6. He will make tests after the engine is installed and 
see to it that the maker has fulfilled his warranties. 

Specifications. — Since engines and gas-producers are 
constructed for commercial ends, it naturally follows 
that their manufacturers seek to make the utmost possi- 
ble profit in selling their installations. Prices charged 
will necessarily vary with the quality of material em- 
ployed, the care taken in constructing the engine and 
generator, the number of apparatus nf the same type 
which are manufactured, the arrangement of the parts 
and that of the installations. Since there is considerable 
rivalry among gas-engine builders, selling prices are 
often cut down so far that little or no profit is left. It 
is very difficult — indeed impossible — to convince a pur- 
chaser that it is to his interest to pay a fair price in order 
to obtain a good installation, especially when other 
manufacturers are offering the same installation at a less 
price with the same warranties. As a result of this state 
of affairs, engine builders, in order that they may not 
lose an order, are willing to reduce their prices, hoping 


to make up in the quality of the workmanship and the 
material what they would otherwise lose. Often thev 
will deliver an engine too small in size but operating at 
a higher speed than that ordered; or they will select an 
old type, or carry out certain details with no great care. 

This, to be sure, is not always the case; for there are 
a few builders of engines who place their reputation 
above everything else and who would rather lose an 
order than execute it badly. Others, unfortunately, 
prefer to have the order at all costs. 

By retaining a consulting engineer, all these diffi- 
culties are overcome. In the first place, the engineer 
draws up a scale of prices and specifications which must 
be complied with in their entirety as well as in all de- 
tails. Rival engine builders are thus compelled to 
make their estimates according to the same standard, 
so that one engine can readily be compared with an- 
other with the utmost fairness. In these specifications, 
penalties will be provided for by the engineer which 
will be levied if the warranties of the maker are not ful- 
filled. Otherwise the warranties are worth nothing. 

The first consequence of engaging a consulting en- 
gineer is to render the matter of cost a secondary one. 
A factory owner who employs a consulting engineer 
and pays him for his services, is impelled chiefly by the 
desire to obtain a good installation -which will perform 
what he expects of it. For that reason necessary sacri- 
fices will be made to comply with the client's wishes. 

If the purchaser considers the question of cost most 
important to him, he need not engage an expert to 


supervise the installation of his engines. He has simply 
to pick out the cheapest engine. Unfortunately, how- 
ever, the money which he will save by such a procedure 
will be more than compensated for by the trouble which 
he will later experience when his motor stops or w r hen 
it breaks down, because it has been cheaply built in the 
first place. 

The advice of a consulting engineer is therefore of 
importance to the purchaser, because an engine will be 
installed which will in every way meet his require- 
ments. The gas-engine builder will also prefer to deal 
with an engineer, because the engineer can appreciate 
at their true worth good material and good workman- 
ship and place a fair valuation upon them. The specifi- 
cations of a gas-engine and gas-producer expert are ac- 
cepted by most engine builders, because an expert will 
not introduce conditions which cannot be fulfilled. 
Some manufacturers refuse to consider the conditions 
imposed by specifications seriously, or else they fix dif- 
ferent prices and make tenders on the basis of these 
with or without specifications. In either case the pur- 
chaser may be sure that he is not receiving what he has 
a right to exact. 

Testing the Plant.— When the engine has been 
selected the consulting engineer supervises its installa- 
tion, and, after this is completed, carries out tests in 
order to determine whether or not the guaranteed 
power and consumption are attained. The methods 
employed in testing a gas-engine are both complex and 
delicate. The quality of the gas, the proportions of the 

the e 


elements forming the mixture, the time and the method 
of ignition, the temperature of the cylinder-walls, the 
temperature and the pressure of the gas drawn into the 
cylinder, all these are factors which have a decided 
bearing upon the results of a test. If these factors be 
not carefully considered the conclusions to be drawn 
from the test may be absolutely wrong. 

Indicators of any type should not be indiscriminately 
employed; only those specially designed for gas-engine 
purposes should be used. Indicator cards are in them- 
selves inadequate, and should be supplemented by the 
records of explosion-recorders. 

The calorific value of the gas should be measured 
either by the Witz apparatus or by means of any other 

In interpreting the diagrams and records some dif- 
ficulty will be encountered. Sometimes it happens that 
a particular form of curve is attributed to a cause en- 
tirely different from the real one. It happens not infre- 
quently that engineers, whose experience is confined to 
engines of one make and who have not had the oppor- 
tunity to make sufficient comparisons, draw such erro- 
neous conclusions from cards. 

To recapitulate what has already been said, the test- 
ing of gas-engines requires considerable experience and 
cannot be lightly undertaken. Special instruments of 
precision are necessary. The author has very often been 
called upon to contradict the results obtained by ex- 
perts whose tests have consisted simply in ascertaining 
the engine power either by means of a Prony brake, or 


by means of a brake-strap on the fly-wheel. The brake 
gives but crude results at best; it is a means of control, 
and not an instrument of scientific investigation. 

Something more than the mere power produced by 
an engine should be ascertained. The tests made should 
throw some light upon the reasons why that power can- 
not be exceeded, and show that the necessary changes 
can be made to cause the engine to operate more eco- 
nomically and to yield energy of an amount which its 
owner has a right to expect. The indicator and the 
recorder are testing instruments which clearly indicate 
discrepancies in operation and the means by which they 
may be corrected. The tests made should determine 
whether the power developed is not obtained largely by 
means of controlling devices which cause premature 
wearing away of the engine parts. 

It is not the intention of the author to describe indica- 
tors of the well-known Watt type. It is simply his pur- 
pose to call attention to the explosion-recorder which 
he has devised to supplement the data obtained by 
means of the indicator. 

Explosion-Recorder for Industrial Engines. — The 
explosion-recorder illustrated in Fig. 145 can be 
adapted to any ordinary indicator. It is composed of 
a supporting bracket B upon which a drum T is 
mounted. This drum is rotated by a clock-train, the 
speed of which is controlled by means of a special com- 
pensating governor. The entire system is pivotally 
mounted upon the supporting screw O, so that the drum 
T, about which a band of paper is wound, may be 


Fig. 145. — Mat hot explosion -recorder. 


swung against a stylus C, which records upon the paper 
the number and power of the explosions. These explo- 
sions are measured according to scale by a spring con- 
nected with an indicator. The records obtained dis- 
close for any given cycle the amount of compression as 
well as the force of the explosion, and render it possible 
to study the phenomena of expansion, exhaust, and suc- 
tion. They are, however, inadequate in showing ex- 
actly how an engine runs in general. Indeed, in most 
gas-engines,, as well as oil and volatile hydrocarbon en- 
gines, each explosion differs from that which follows in 
character and in power; and it is absolutely essential to 
provide some means of avoiding these variations. The 
explosion-recorder gives a graphic record from which 
the number of explosions can be read, and also the ini- 
tial pressure of each explosion, the number of corre- 
sponding revolutions, the order in which the explosions 
succeed one another, and consequently the regularity of 
certain phenomena caused by secondary influences, such 
as the section of the distributing members, the sensitive- 
ness of the governor, and the like. 

The explosion-records can be taken simultaneously 
with ordinary diagrams. In order to attain this end, 
the recorder is allowed to swing around the pivot O, so 
that the drum carrying the paper band is brought into 
engagement, or swung out of engagement with the 
stylus, as it is influenced by each explosion, thereby 
leaving its record on the paper. The ordinary diagram 
may be traced on the drum of the indicator, as it con- 
tinues to operate in its usual way. Thus the explosion- 


recorder renders it possible to control the operation of 
engines, to obtain some idea of the cause of defects and 
to attribute them to the proper force. Improvements 
can then be made which will ensure a greater efficiency. 
A number of records herewith reproduced illustrate the 
defects in the controlling apparatus and in the construc- 
tion of certain engines, and also the result of improve- 
ments which have been made on the basis of the records 
obtained. The smaller lines indicate the compression, 
which is usually constant in engines in which the " hit- 
and-miss " system of governing is employed, while the 
larger lines indicate the explosions. These records are 
only part of the complete data normally drawn on the 

Fig. 146. — Record with 

paper in the period of 120 seconds corresponding with 
an entire revolution of the recorder-drum. 

The first record was taken while starting up an en- 
gine provided with an automatic starting device and 
supplied with explosive mixture without previous com- 
pression {Fig. 146). The gradual lessening of the dis- 
tances of the ordinates or lines representing the explo- 
sions shows that the speed of the motor was slowly 
increasing, and also indicates the time which elapsed 
before the engine was running smoothly. The records 
that follow (Figs. 147, 148 and 149) show the results 


which can be obtained with the recorder by correcting 
the errors due to faults in installing the engine and its 

Fig. 147. — Gas-engine-r 

ing at one-half load. 

accessories. The fifth record is particularly interesting 
because it shows the influence of the ignition-tube on 

FlG. 148. — Record made after 

the power of the deflagration of the explosive mixture 
(Fig. 150). This record was obtained with an engine 

Fig. 149. — Record made after correcting faults. 

provided with two contiguous tubes. The communica- 
tion of each of these tubes with the explosion-chamber 


could be cut off at will at any moment. The last record 
(Fig. 151) was obtained at a time when the effective 
load of the engine was changed at two different inter- 
vals. This record shows how regularly the engine was 
running and how constant were the initial pressures. 
These pressures, however, which is the case in mos: 
engines, manifestly diminish when the explosions suc- 
ceed one another without idle strokes of the piston. 
This shows, also, the influence of "scavenging" the 
products of combustion and the effect it has on the 
efficiency of explosion-engines. 

Analysis of the Gases.— It has already been stated 
that one of the tests which should be made consists in 
measuring the calorific value of the gas. Just what the 
calorific value of the gas may be it is necessary to know 
in order to obtain some idea of the thermal efficiency of 
the installation. If a suction gas-producer be employed 
(an apparatus in which the nature of the gas generated 
changes at each instant) , calorimetrical analyses are in- 
dispensable in appreciating the conditions under which 
a generator operates. 

These analyses are made by means of calorimeters 
which give the calorific value either at a constant 
pressure or at a constant volume. 

Constantrvolume instruments give a somewhat 
weaker record than constant-pressure instruments; but 
according to Professor Aime Witz, the inventor of an 
excellent calorimeter, the constant-volume type is al- 
most indispensable in gaging the efficiency of explo- 

si?co£:v!N-sz *>.>*-»> 



The Witz Calorimeter. — The accompanying dia- 
gram (Fig. 152) illustrates Professor Witt's instru- 
ment. Its elements are a steel cylinder having an inte- 
rior diameter of 2.36 inches, about a thickness of 0.078 
inch and a height of about 3.54 inches, so that its capac- 
ity is about 15.1 cubic inches, and two covers screwed 
on the cylinder to seal it hermetically, oiled paper be- 
ing used as a washer. The upper cover carries a spark- 

Fig. 152. — The Witz calorimeter. 

exciter; the lower cover is provided with a valve which 
discharges into a cylindrical member 1.06 inches in 
diameter. This second cover is downwardly inclined 
at its circumference toward the center to insure com- 
plete drainage of the mercury used for charging the 
calorimeter. All surfaces are nickel plated. The 
proportions of nickel and of steel are fixed by the 
manufacturer so as to render it possible to calculate the 
displacement of the apparatus in water. The calo- 
rimeter having been completely filled with mercury is 
inverted in this liquid in the manner of a test tube. The 


explosive mixture is then introduced, being fed from 
a bell in which it has previously been prepared. A 
rubber tube connects the bell with the instrument. 
The gas is forced from the bell to the calorimeter by 
the pressure in the bell. The conical form of the bot- 
tom causes the calorimeter to be emptied rapidly and 
to be refilled completely with explosive gas at a pres- 
sure slightly above that of the atmosphere. Equi- 
librium is re-established by manipulating the valve, 
during a very short interval, so as to permit the excess 
gas to escape. During this operation the calorimeter 
must be maintained in the vertical position shown in the 
diagram. The atmospheric pressure is read off to one- 
tenth of a millimeter (0.003936 inches) on a barometer. 
The temperature of the gas may be taken to be that of 
the mercury- vessel. 

The explosive mixture is prepared in the water res- 
ervoir, the glass bulb shown in the accompanying illus- 
tration being employed. This bulb is closed at its 
upper end by means of a cock and is tapered at its lower 
end. The gas or air enters at the top by means of a 
rubber tube and gradually displaces the water through 
the lower end. The bulbs have a volume varying from 
200 to 500 cubic centimeters (12 to 30 cubic inches), 
and the error resulting from each filling of a bulb is 
certainly less than 15 cubic millimeters (0.0009 cubic 
inches) . The contents are emptied into a bell by lower- 
ing the bulb into the water and opening the cock. If 
seven bulbfuls of air be mixed with one bulbful of gas, 
an explosive mixture of 1 to 7 is produced, this being 


the proportion commonly employed for street-gas. For 
producer-gases the preferred proportion is i to i, oxy- 
gen being often added to the air in order to insure com- 
plete combustion. 

The calorimeter, after having been filled, is placed 
in a vessel containing a liter (1.7598 pints) of water 
so that it is completely immersed. A spark is then 
allowed to pass. The explosion is not accompanied by 
any noise; the temperature rises a fixed number of 
degrees, so that the quantity of heat liberated can 
easily be computed. Each division of the thermometer 
is equal to 0.01502 C. The scale reading is minute, 
each interval being divided by ten, so that readings to 
the 1,500th part of a degree can be taken. 

It should be observed that the mixture generated in 
the reservoir is saturated with water vapor at the tem- 
perature of the reservoir. Consequently, the vapor 
generated by the explosion must condense in the calo- 
rimeter if the final temperature of the calorimeter is the 
same as that of the water reservoir. If, on the other 
hand, the temperature be slightly different, a correction 
must be made; but the error is negligible for differences 
in temperature of from 2 to 3 degrees C. (3.6 to 
5.4 degrees F.). This, however, is never likely to 
occur if the operation is conducted under favorable 

This apparatus is exceedingly simple and practical. 
It does not require the manipulation of a pump. The 
pressure of the mixture is read off on the barometer; the 
calorimeter is entirely immersed in the water of the 



outer vessel, so that all corrections of doubtful accuracy 
are obviated. The method requires but a very slight 
correction for temperature. Air, alone or mingled with 
oxygen, or a mixture of air and oxygen, can be easily 
tested with. 

Maintenance of Plants. — If it should be necessary 
to retain a consulting engineer to install an engine 
capable of filling all requirements, it is also necessary 
to select a careful attendant in order that the engine 
may be kept in good condition. It is a rather wide- 
spread belief that a gas-engine can be operated without 
any care or inspection. This belief is all the more 
prevalent because of the employment of street-gas en- 
gines, which, by reason of their simplicity of construc- 
tion and regularity of fuel supply, often run for several 
hours, and even for an entire day, without any attention 
whatever. But this negligence, particularly in the case 
of engines driven from producers, is likely to produce 
disastrous results. Although engines of this type do not 
require constant inspection during operation, still they 
require some attention in order that the speed may be 
kept at a fixed number of revolutions. Moreover, 
the care of the engine, the cleaning of the valves and of 
the various parts which are likely to become dirty, and 
the examination and cleaning of pipes, should be ac- 
complished with great care and at regular intervals. 
This task should be entrusted only to a man of intelli- 
gence. A common workman who knows nothing of 
the care with which the parts of an engine should be 
handled is likely to do more harm than good. 


The factory owner who follows the instructions 
which have been given in this book will avoid most of 
the stoppages and the trouble incurred in engine and 
generator installations, and may count upon a steadiness 
of operation comparable with that of a steam-engine. 


Made by R. Mathot at the Works of the "Union Electrique" 

C ie , Brussels, June 27, 1901 

Piston Diameter : 15)4"- Piston stroke, 22". 
Normal number of revolutions, 210. 


1. Calorific value of the coal 12750 B.T.U. 

2. Nature and origin of fuel: Anthracite coal 

of Charleroi (Belgium). 

3. Cost of fuel per ton at the mine .... $5.50 

4. Cost of fuel per ton at the plant .... $6.39 

5. Fuel consumption per hour in the generator . 46.3 lbs. 

6. Fuel consumpton per hour in the boiler 7 lbs. 

7. Proportion of ash in the coal .... 6 per cent. 

8. Weight of steam at 66 lbs. generated per 

hour 42.7 lbs. 

9. Average brake horse-power 53 B.H.P. 

10. Fuel consumption for gas per B.H.P. per 

hour 0-875 'bs. 

11. Fuel consumption for steam per B.H.P. per 

hour °- l 3i J^s. 

12. Total fuel consumption 1.008 lbs. 

13. Steam consumption at 66 lbs. pressure . 0.81 lbs. 

14. Gas pressure at the engine 1^6 inches 

15. Weight of water per B.H.P. per hour for 

cooling the cylinder entering at 68° F. 

and leaving at 105 F 5 1. 5 lbs. 


16. Corresponding heat absorbed in cooling . 1970 B.T.U. 

17. Average initial explosive pressure on piston 324 lbs. 

18. Average pressure on piston per square inch 72 lbs. 

19. Average indicated horse- power with 85 per 

cent, misses 92.5 I.H.P. 

20. Corresponding mechan'cal efficiency 84 per cent. 

21. Corresponding electric load 31.950 K.W. 

22. Cost of B.H.P. per hour in anthracite . #0.0029 

23. Cost of kilowatt per hour in anthracite . $0.0048 

24. Electric power generated per B.H.P. . 602.8 W. 

25. Thermal efficiency at 53 B.H.P. with 85 

per cent, explosions 18.5 per cent. 


With Winterthur Suction-Producer made by R. Mathot at Winter- 

thur, June 4 and 5, 1902 


Dimensions of Winterthur Engine — Piston diameter: io-ia". Stroke: 

16^6". Compression: 177 pounds per square inch. Regulation: 

, hit and miss. Ignition: electro-magnetic. Fly-wheel: normal, 

with external bearing. Lubrication of piston: with oil-pump. 

Of main bearings, with rings (as in dynamos). 


1. Number of revolutions per minute . . 200 

2. Corresponding number of explosions . . 96 per cent. 

3. Net load on brake 120 lbs. 

4. Corresponding effective power . . 22 B.H.P. 

5. Mean initial explosive pressure on piston 

per square inch 455 lbs. 

6. Average pressure on piston per square inch 78 lbs. 

7. Gas consumption per B.H.P. at 24° C. and 

721 mm. mean pressure 15.5 cubic feet 

8. Gas consumption per B.H.P. reduced to 

o° C. and 760 mm. mean pressure 13.5 cubic feet 



9. Number of revolutions per minute . . . 204 

10. Corresponding number of explosions . 60 percent. 

11. Net load on brake 60 lbs. 

12. Corresponding effective power . . . . 11.6 B.H.P. 

13. Gas consumption per B.H.P. per hour at 

24 C. and 721 mm. mean pressure . 21 cubic feet 

14. Gas consumption per B.H.P. per hour at 

o° C. and 760 mm. mean pressure . . 18.3 cubic feet 



15. Number of revolutions per minute . . . 206 

16. Corresponding number of explosions . 22 per cent. 

17. Total gas consumption per hour at 24 C. 

and 721 mm. mean pressure .... 106 cubic feet 

18. Maximum calorific power of gas per cubic 

foot 598 B.T.U. 

19. Thermal efficiency with 96 per cent, explo- 

sions 31 per cent. 

20. Mechanical efficiency with 96 per cent, ex- 

plosions 82 per cent. 

21. Temperature of water at the jacket-inlet . 75 degs. F. 

22. Temperature of water at the jacket-outlet 130 degs. F. 

23. Compression per square inch on piston sur- 

face 178 lbs. 

24. Pressure after expansion 37 lbs. 


1. Nature of fuel. Belgian an. hracite, "Bonne 

Esperance et Batterie"; size, ^ inch. 

2. Chemical compositon: Carbon, 86.5 per 

cent.; hydrogen, 3.5 per cent.; oxygen 
and nitrogen, 4.65 per cent.; ash, 5.35 per 

3. Calorific value per pound of coal . . . 14200 B.T.U. 


4. Net calorific value per pound of fuel 

5. Price of anthracite delivered at the plant 

6. Number of revolutions of engine per minute 

7. Corresponding number of explosions 

8. Load on brake 

9. Corresponding effective horse-power 

10. Fuel consumption at the generator per hour 

11. Fuel consumed per B.H.P. per hour 

12. Proportion of ash resulting from the tests 

13. Mean initial explosive pressure per square 


14. Average pressure on piston per square inch 

15. Indicated horse-power with 91 per cent, ex- 


16. Mechanical efficiency 

17. Thermal efficiency at the producer . 

18. Water consumption per hour in the scrubber 

19. Cost per B.H.P. per hour in anthracite 

15050 B.T.U. 
S3. 50 per ton 
91 per cent. 
106 lbs. 
20.2 B.H.P. 

16.4 lbs. 
0.81 lbs. 

6 per cent. 

419.5 lbs. 

72.5 lbs. 

25.4 I.H.P. 
79 per cent. 
22 per cent. 
66 gals. 
62 gals. 


(Made at Cologne, March 15, 1904, by R. Mathot.) 


Diameter of Piston = 16.5". Piston Stroke = 18.9" 


1. Average number of revolutions per minute 

2. Corre ponding effective work 

3. Average compression per square inch 

4. Average n t'al explosive pressure per square 


5. Average final expansion pressure 

6. Vacuum at suction 

7. Average pressure on piston . 

8. Corresponding indicated horse- power 


65.11 B.H.P. 
176 lbs. 

397 !bs - 
25 lbs. 

4 .4 lbs. 

81 lbs. 

77 I.H.P. 

Sulphur . 

. 0.44 % 


■ 7 -33 % 

Water . . 

. 2.69 % 



9. Nature of fuel : Anthracite coal 0.4" to 0.8" 

10. Origin: Coalpit of Ze he, Morsbach at Aix- 

la-Chape le. 

1 1 . Chemical composition of coal : 

Carbon . . . . 83 .22 % 
Hydrogen . . . 3.31 % 
Nitrogen and Oxygen 3 .01 % 

12. Calorific value 13650 B.T.U. 


13. Chemical composition of gas: 

Carbonic acid 6 .60 % Methane ... o .57 % 

Oxygen . o .30 % Carbon monoxide 24 .30 % 

Hydrogen . 18 .90 % Nitrogen. . . 49 .33 % 

14. Calorific value of gas, combination water, 

at 59 F. constant vo ume reduced to 

32 F. and atmospheric pressure . . . 140 B.T.U. 



15. Cooling water at the inlet of the cylinder- 

head 55 *4 deg. F. 

Temperature at the outlet .... 109 .5 deg. F. 

16. Temperature at outlet of cylinder . 127 .5 deg. F.. 


17. Temperature of water in the vaporizer . . 158 .3 deg. F. 


18. Mechanical efficiency 84 .6 % 

19. Gross consumption of coal per B. H. P. per 

hour o .86 lbs. 

20. Thermal efficiency in proportion to the ef- 

fective work and the gross consumption 

of coal in the gas-generator .... 24 .3 % 



33 ,85 B.H.P. 

125 lbs. 

258 lbs. 

18 lbs. 
6 .8 lbs. 

46 .2 lbs. 

45 . I.H.P. 

3 -5 /c 



1. Average number of revolutions per minute 

2. Corresponding effective work 

3. Corresponding average compression 

4. Average initial explosive pressure 

5. Average final expansion . 

6. Vacuum at suction .... 

7. Average mean pressur. on piston 

8. Corresponding indicated power . 

9. Speed variation between full and half load 


10. Gross consumption of coal per B.H.P. per 

hour 1 .155 lbs. 


1. Average number of revolutions per minute 

2. Minimum corresponding compression 

3. Average initial explosive pressure 

4. Average final expansion .... 

5. Vacuum at auction 

6. Average pressure on piston 

7. Corresponding indicated horse-power 

8. Speed variation between full load and no 










11 .2 





5 •* Vc 


March 14 and 15, 1904, by Me rs. A. Witz, R. Mathot, and de 



Piston Diameter: 21 }£". Stroke: 27^". Diameter of Piston-Rods : 

front, 43.^; rear, 4 fr* 



Full Load Tests 
i. Average number of revolutions per minute 151.29 and 150.20 

2. Corresponding effective load . 214.22 B.H. P. and 222.83 B.H.P. 

3. Duration .of the tests 3 hours and 10 hours 

4. Average temperature of water after cooling 

the piston JI 7-5 deg. F. 

5. Average temperature of water after cool- 

ing the cylinder and valve-seats . . 135 deg. F. 

6. Water consumption per hour for cooling the 

piston 39 gal. 


7. Nature and Origin of Fuel: Anthracite 

coal " Bonne-Esperance et Batterie" 
Herstal, Belgium. 

8. Calorific value of fuel 14650 B.T.U. 

9. Consumption of fuel per hour (plus 53 lbs. 

on the night of the 14th for keeping the 
generator fired during 14 hours, the en- 
gine being stopped) 199 lbs. — 160 lbs. 

10. Water consumption per hour in the vapor- 

iser 14.2 gals. 

11. Water consumption per hour in the scrub- 

bers 318 gals. 

12. Average temperature of gas at the outlet 

of the generator 558 deg. F. 

13. Average temperature of gas at the outlet 

of the scrubbers 62.5 deg. F. 


14. Gross consumption of coal per B.H.P. per 

hour 0.927 lbs. — 0.720 lbs. 

15. Consumption of coal per B.H.P. after de- 

duction of the water 0.907 lbs. — 0.705 lbs. 



16. Thermal efficiency relating to the effective 

H.P. and to the dry coal consumed in 

the generator 19% — 24.4% 

17. Water consumption per B.H.P. hour: 

For the cylinder, stuffing-boxes and valve- 
seat jackets 4.65 gals. 

For the piston and piston-rods ... 1.75 gals. 

For the vaporizer 0-0655 gals. 

For washing the gas in the scrubbers . 1.42 gals. 

18. Water converted in steam per lb. consumed 

in the generator °* l 93 gals. 


Adjustment of gas-engine, 126 

Adjustment of moving parts, imper- 
fect, 146 

Admission -valve, binding of, 152 

Admission, variable, 55, 56 

Air-blast, 180 

Air-chest, 82 

Air, displacement of, 92 

Air, exclusion of, in producers, 207 

Air, filtration of, 82 

Air-heater, Winterthur, 236 

Air-heaters, 238 

Air-pipe, 82 

Air-pipe, location of, 8^ 

Air-pump, 266 

Air, regulation of supply, 82 

Air suction, 81 

Air suction, resistance to, 82 

Air supply of producer, 225 

Air-valve, control by engine, 25 

Air vibration, 92 

Alcohol as engine fuel, 264 

Anthracite, consumption of, in pro- 
ducers, 200 

Anthracite in producers, 190, 201 

Anti-pulsators, 77 

Anti-pulsators, disconnection of, in 
stopping engine, 132 

Anti-pulsators, precautions to be 
taken with, 79 

An ti -vibrator}- substances, 89 

Ash-pit, 214, 217 

Ash-pit, Bollinckx, 220 

Ash-pit, cleaning of, 261 

Ash-pit, Deutz, 220 

Ash-pit, door of, 220 

Ash-pit, Wiedenfeld, 220 

Asphyxiation, 169 

Atomizer of oil-engines, 265 


Back firing, 82, 131 

Back pressure to exhaust, 151 

Bags, arrangement of, 80 

Bags, capacity of, 79 

Bags, precautions to be taken with, 79 

Bags, rubber, 77 \ 

Bark as producer fuel, 193 

Batteries for ignition, 31 

Bearings, adjustability of, 5 

Bearings, adjustment of, 44 

Bearings, care of, 123 

Bearings, lubrication of, 117 

Bearings, material of, 51 

Bearings of fly-wheels, 92 

Bearings, overheated, 146 

Bearings, over-lubricated, 150 

Bearings, position of, 44 

Bell, gas-holder, 187 

Bell, Pintsch, 248 

Bell, volume of, 187 

Belts, prevention of adhesion by oil, 

Benier, E., 199 

Benzin as engine fuel, 264 

Binding, 147 

Blast in producers, 180, 193, 225 

Blower, Koerting, 181 

Bl v.ver, Root, 182, 188 

Blowers for producers, 181 

Blowing-generators, 169 

Bolts of foundation, 91 

Bomb, Witz, 284, 292 

Boughs for coolers, 108 

Box, charging, 221 

Box, double closure for charging, 222 

Box, removable charging, 225 

Brake tests, 284 

Branch pipes, minimum diameter of, 

Bricks for foundation, 91 

Brushes, lifting of, when dynamo- 
engine is stopped, 132 

Brush, purifying, 250 

Burner of hot tube, how ignited, .128 

Burner, regulation of fixed, 144 

Bushings, care of, 123 

Bushings, fusion of, 147 

Bushings (see also Bearings) 


306 INDEX 


Consumption at half load and full 

load, 62 

Calorimeter, Witz, 393 

Consumption at various loads, 62 

Calorimeters, 284, 390 

Consumption in double or triple act- 

Cam, half -compression, 130, 133 

ing engines, 62 

Cam, relief, 130 

Consumption of gas, 173 

Cams, 51 

Consumption of gas in burner, 30 

Caps of valve-chests, 134 

Consumption of suction-producers, 

Carbureter, 366 

Care during operation of engine, 131 

Consumption per effective horse- 

Casing, independence of frame, 43 

power, 62 

Charing a producer, 221 

Cooler for gas, 199 

Charging the generator, 259 

Cooler, for producer, 240 

Chest for exhaust, 83 

Circulation of water, o3, 125 

Coolers, size of, 109 

Circulation of water, how effected, 

Cooling of cylinder, 08, 100, 156 


('imling of producer-gas engines, 203 

Circulation of water in tanks, 105 

Cooling, thermo-siphon, 100 

Circulation of water, regulation of, 

Cost of oil and volatile hydrocarbon 


engines, 368 

Cleaning of producer, 261 

Crank-pin, tensile strength of. si 

Cleanliness, necessity of, 131 

Crank-shaft, 50, 51 

Cleanliness of producers, 179 

Crank-shaft bearings, 44 

Closures for charging-boxes, 233 

Crank-shaft bearings, design of, 46 

Coal in producers, 201 

Crank -shaft, effect of premature ex- 

Coal in producers, bituminous, 195 

plosion on, 30 

Coal, Pennsylvania, 203 

Crank -shaft lubrication, 117 

Coal (see also Anthracite) 

Crank-shaft, material of, 50 

Coal, Welsh, 303 

Crosshead, care of, 123 

Cock, Deutz, 224 

Cycle, analysts of, 376 

Cock, Pierson, 224 

Cylinder, arrangement of, 41 

Cock for charging-bos, 233, 334 

Cylinder, cleaning of, 122 

Coke in producers, 201 

Cylinder, cooling of, 156 

Coke in washers, 242 

Cylinder, evacuation of, 83, 131 

Combustion -generators, 193 

Cylinder, gravel in, 137 

Combustion, inverted, 195 

Cylinder, grinding of, 42 

Compression, determination of, 273 

Cylinder, incandescent particles in, 

Compression, faulty, 134 


Compression, high, 154 

Cylinder, independence of casing, 

Compression in Bank! engine, 264 


Compression in Diesel engine, 364 

Cylinder-jacket (see Water-jacket) 

Compression, losses in, 143 

Cylinder lubrication, 112 

Compression period, 21 

Cylinder-oil. 112, 149 

Compression, relation to power de- 

Cylinder, overhang in horizontal en- 

veloped, 133 

gines, 43 

Compressors for producers, 182 

Cylinder, overheating of, 148 

Connecting-rod bearings, 45 

Cylinder, presence of water in, 136 

Connecting-rod bearings, rational de- 

Cylinder-shell, 41 

sign of, 45 

Cylinder, smoke from, 149 

Connecting-rod, lubrication of, 113, 

Cylinder, temperature during opera- 


tion of engine, 132 

Consulting engineer, advisability of 

Cylinder, thrust of, 43 

retaining, 28a 

Cylinder, tightness of, I» 



Damper, Pintsch, 224 

Dampers, 223 

Detonations, untimely, 141 

Distributing mechanism, derange- 
ment of, 152 

Drain-cock in gas-pipes, 70, 75 

Drain-cocks, testing of, 256 

Drier for producer-gas, 248 

Dust-collector, 239 

Dust-collector, Benz, 239 

Dust-collector, Bollinckx, 239 

Dust-collector, Pintsch, 239 

Dust -collector, Wiedenfeld, 239 

Dynamo, lifting brushes from, in stop- 
ping engine, 132 

Ebelmen principle, 195 
Engine, Banki, 264 
Engine, Diesel, 264 
Engine, producer-gas and steam, com- 
pared, 203 
Engine, selection of, 279 
Engine, starting a producer-gas, 258 
Engineer, duty of a consulting, 281 
Engines, governing oil, 265 
Engines, oil, 264, 265 
Engines, producer-gas, 153 
Engines, producer-gas, temperature 

of, 157 
Engines, specifications of, 281 

Engines, speed of oil, 264 

Engines, tests of, 268 

Engines, volatile hydrocarbon, 264, 

Engines, writers on oil, 266 
Escape-pipes, 228 
Essences, 264 
Exhaust, 83 

Exhaust, back pressure to, 151 
Exhaust, determination of resistance 

to, 274 
Exhaust into sewer or chimney, 85 
Exhaust, noises of, 94, 141 
Exhaust period, 22 
Exhaust, water in, 136 
Exhausters, 183 
Exhaust-chest, 83 
Exhaust-muffler, 86, 94 

Exhaust-pipe, 83, 85 

Exhaust -pipe, design of, 96, 97 

Exhaust -pipe, joints for, 85 

Exhaust -pipe, oil in, 151 

Exhaust -valve, binding of, 152 

Exhaust -valve, cooling of, 25 

Expansion -boxes, 95 

Expansion period, 22 

Expert, necessity of an, 282, 283 

Explosion, spontaneous, 140 

Explosion -engines (see Gas-engines) 

Explosion period, 22 

Explosion -recorder, analysis of inertia 
of, 277 

Explosion -recorder for industrial en- 
gines, 285 

Explosion-recorder, the continuous, 

Explosions, comparison of average 
force of, 275 

Explosion -records, 288 

Explosions, retarded, 143 

Fans for producers, 181 

Feeder, Winterthur, 236 

Feed-hopper, 224 

Firebox, door of, 221 

Flues, escape, 228 

Fly-wheel, oil on, 120 

Fly-wheel, starting the, 131 

Fly-wheels, 46 

Fly-wheels as pulleys, 46 

Fly-wheels, balancing of, 46 

Fly-wheels, curved spoke, how 
mounted, 49 

Fly-wheels, fastening of, 46 

Fly-wheels, proper mounting of, 46 

Fly-wheels, rim of, 46 

Fly-wheels, single, 48, 92 

Fly-wheels, single, for dynamo-en- 
gines, 46 

Fly-wheels, straight and curved 
spoke, 49 

Fly-wheels with hit- and- miss system, 

Foundation, 44, 87 
Foundation, design of, 88, 89 
Foundation, excavation for, 88 
Foundation, insulation of, 89, 90 
Foundation of dynamo-engine, 91 

3° 8 

Frame, 43 

Frame, method of securing, lo foun- 

'liiiinii, 11 
Fuel of producers, 178, 187, 254 
Fuel, qualities of, 201 
Fuel {see also I, ignite, Peal, Sawdust, 

Wood, Coal, etc.) 
Fuel, size of, 201 
Fuel, smoke -producing, 254 

Gas, ascertaining purity of, 128 

Gas, blast-furnace, 153 

Gas, calorific value of, 284 

Gas, calorific value of producer, 

Gas, coke-oven, 153 

Gas consumption, 173 

Gas consumption of burner, 30 

Gas, effect of quality, 15a 

Gas-engine, balancing of, 46 

GaB-engine, care during operation, 

Gas-engine, cost of installation, to 
Gas-engine, cost of operation, 19 
Gas-engine, difficulties in starting, 

Gas-eogine, bow to start a, n8 
Gas-engine, how to stop a, 132 
Gas-engine, installation of a, 68 
t las-engine, location of a, 68 
Gas-engine, selection of a, 21 
Gas-engine, simplicity of installation, 

Gas-engine, the four-cycle, 21 
Gas-engines, adjustment of, 126 
Gas-engines, care of, 121 
Gas-engines, " Si earn -Hammer," 57 
Gas-engines, temperature of, 158 
Gas-engines, tests of, 283 
Gas-engines, vertical, 56 
Gas-engines, writers on, 68 
Gas, fuel, 1 53 
Gas-holder, 1S6, 1S9 
Gas-holders, 347 
Gas-bolder, combined with washer or 

scrubber, 186 
Gas, illuminating (see Street-gas) 
Gas, impurities of, t73 
Gas, Mood, [53, 167 
Gasometer (see Gas-holder) 

Gas, producer (see Producer-gas i 
< ias [traduction, 173 
Gas, purification of wood, 195 
Gas supply, necessity of coolnes 

Gas-valve, necessity of indepeadai 

operation of, 27 
Gas, water, 153, 169 
Gas, wood, 153, 168 
Gases, analysis of, 290 
Generator (see also Producer) 
Generator, Bens, 307 
Generator. BolKnckx, 207 
Generator, care of, 259 
Geni-r.itnr, charging I In-. _';o 
Generator, construction of, 177, 2 
Generator, dimensions of, 252 
Generator, Dowson, 177 
Generator, liring the, 205, 256 
Generator, hot operation of, 25a 
Generator of suction producer, 205 
Generator, operation of, 251 
Generator, I'ierson, 215 
Generator, I'intsch, 307 
Generator, Taylor, 207 
Generator, Wiedenfeld, 207 

Generator with internal vaporu 

Generators, blowing, 169 
Generators, pressure, 169, 177 
Governor, ball, 51, 53 
Governor, rare during opera tior 

Governor, hit -and- 
Governor, " 
Governors, 53 _ 

'. 5 2 . 54 

Governor*, iidjusnuiT 
Governors, care of, 123 
Governors, centrifugal, 56 
Governors, centrifugal, with 1 

miss regulation, JS 
Governors for oil-engines, 265 
Governors for produc 


Governors, hit-and-miss, 54 
Governors, variable admission, 56 
Grate, Benier's, 216 
Grate of gen era tor- lining, 214 
Grate, Kiderlen, 216 
Grate, Pinlsch, 216 
Grate, Wiedenfeld, 316 




Heater, air, 238 

Hit-and-miss regulation (see Gov- 

Holders, gas, 247 

Hopper, Bollinckx, 225 

Hopper, Deutz, 225 

Hopper for generator, 224 

Hopper, removable feed, 225 

Hopper, Taylor, 225 

Hopper, Wiedenfeld, 225 

Hopper, Winterthur, 225 

Horse-power, definition of, 60 • 

Horse-power, determination of, 61 

Horse-power (see also Power) 

Hot tubes (see Tubes) 

Hydrocarbons, volatile, for engine 
fuel, 264 

Ignition, 27, 122 

Ignition, adjustment of, 144 

Ignition by battery and coil, 31 

Ignition by magneto, ^ 

Ignition, curing defects of electric, 

Ignition, defective, 152 

Ignition, disadvantages of belated, 

Ignition, disadvantages of prema- 
ture, 28 

Ignition, effect of lost motion, 146 

Ignition, effect of mixture composi- 
tion on, 28 

Ignition, effect of temperature of 
flame on, 28 

Ignition, effect of water on, 136 

Ignition, electric, 30, 139 

Ignition, electric, regulation of, 145 

Ignition, faulty, 143 

Ignition for high -pressure engines, 35 

Ignition, hot -tube, 159 

Ignition, imperfect, 137 

Ignition, objections to electric, 31 

Ignition of producer-gas, 160 

Ignition, premature, 139, 142 

Ignition, premature, in high-pressure 
engines, 158 

Ignition, prevention of, by faulty com- 
pression, 134 

Ignition, proper timing of, 27 

Ignition, spontaneous, 140, 159 

Ignition, tests prior to starting en- 
gine, 129 

Ignition -tubes (see Tubes) 

Incrustation of water-jacket, 98, 148 

Incrustation, prevention of, 107 

Incrustations, 255 

Indicators, 285 

Indicator-records, 127 

Induction-coil, 32 

Installation, laws governing gas- 
engine, 86 


Joints, 125 
Joints, care of, 124 

Laming mass, 246 

Laws governing gas-engines, 86 

Leakage of pipes, 69 

Lift -valve for charging-box, 223 

Lignite in producers, 188 

Lining, refractory, 211 

Lining, support for generator, 214 

Loads, consumption at half and full, 

Location of engine, 68 
Lubricate (see Oils) 
Lubricating-pumps, 115 
Lubrication, 111, 121 
Lubrication, difficulties entailed by, 

Lubrication, faulty, 149 
Lubrication of crank-shaft, 117 
Lubrication of high -power engine, 

Lubrication of valve-stem, 1 19 
Lubricator, cotton-waste, 117 
Lubricators, automatic, 113 
Lubricators, disconnection of, when 

stopping engine, 132 
Lubricators, examination of, before 

starting, 129 
Lubricators, feed of, 121 
Lubricators, revolving-ring, 118 
Lubricators, sight-feed, 118 
Lubricators, types of, 113 




Magneto, adaptability for producer- 
gas, 35 
Magneto, control of, 38 

Magneto, efficiency of, 34 

Magneto-igniter, construction of, 35 

Magneto ignition, 33 

Magneto ignition, precautions to be 
taken, 34 

Magneto, inspection of, before start- 
ing engine, 129 

Magneto, mechanical control of, 33 

Magneto, operation of, 33 

Magneto, regulation of, 37 

Maintenance of plants, 295 

Manograph, 269 

Mass, Laming, 246 

Meters, capacity of, 70 

Meters, dry, 72 

Meters, evaporation in wet, 70 

Meters, falsification of records, 70 

Meters, inclination of, 71 

Meters, size of, 71 

Misfire, 137 

Mixture, effect of high compression 

in > J 55 
Mixture, effect of high pressure on, 


Mixture, governing by varying the, 

Mixture, poorness of, 143 

Mixture, pressure of, 26 

Mixture-valve, necessity of independ- 
ence of ojx.Tation of, 27 

Mortar for foundation, 87 

Motion, lost, 146 

Muffler for exhaust, 86, 94 


Naphthalene in gas-pipes, 70 
Noises, cause of, 92 
Noises of exhaust, 94 


Oilers (see Lubricators) 
Oiling (see Lubrication) 
Oil, addition of sulphur to, 147 
Oil, cylinder, 149 
Oil-engines, 264, 265 

Oil-engines, governing, 265 
Oil-engines, speed of, 264 
Oil-engines, writers on, 266 
Oil for engine fuel, 264 
Oil, freezing of, 150 
Oil-guard for fly-wheel, 120 
Oil-lamp, 266 

Oil, prevention of spreading on fly- 
wheel, 120 
Oil-pumps, 115, 226 
Oil, quality of, 150 
Oil, splashing of, 119 
Oil-tank, 266 
Oils, how tested, 112 
Oils, mineral for lubrication, 112 
Oils, purification of, 1 13 
Oils, quality of, 112 
Oils, requisites of, 112 
Operation, steadiness of, 52 
Otto cycle, 21 
Overheating, 152 
Overheating, prevention of, 147 

Pacini treatment, 171 

Peat in producers, 188 

Perturbations, 134 

Petrol (see Oil) 

Pipe-hangers, 86 

Pipes, 69 

Pipes, cross-section of, 70 

Pipes, disposition of, 77 

Pipes, escape,' 228 

Pipes, exposure to cold, 69 

Pipes for exhaust, 83 

Pipes for producer-gas, 249 

Pipes for water-tanks, 102, 103, 105 

Pipes, hanging of, 86 

Pipes, insulation from foundations 
and walls, 94 

Pipes, leakage of, 69 

Pipes, minimum diameter of branch, 

Pipes, proper size of, 70 

Piston, 39, 122 

Piston, avoidance of insertions or 
projections, 39 

Piston, cleaning of, 141 

Piston, curved faces inadvisable, 39 

Piston, direct connection with crank- 
shaft, 43 


3 11 

Piston, finish of, 41 

Piston, importance of, in 

Piston, leakage of, 136 

Piston, overheating of, 148 

Piston, position of, in starting, 130 

Piston, rear face of, 39 

Piston-pin, construction of bearing 
at, 40 

Piston-pin, location of, 41 

Piston-pin, locking of, 40 

Piston-pin, lubrication of, 113 

Piston-pin, material of, 40, 51 

Piston-pin, strength of, 40 

Piston-rings, fouling of, 149 

Piston -rings, material of, 41 

Piston-rings, number of, 41 

Piston-rod, effect of premature ex- 
plosion on, 30 

Piston-wear, 40 

Poisoning, carbon monoxide, 170 

Porcelain of spark-plug, $2 

Power, definition of, 60 

Power, measuring engine, 285 

Power, " Nominal," 61 

Precautions to be taken in starting, 

Pressure, back, to exhaust, 151 

Pressure-generators, 169, 177 

Pressure in producer-gas engines, 160 

Pressure-lubricators, 114 

Pressure-producers, 1 74 

Pressure-regulator, bell as, 187 

Pressure- regulators, 77 

Pressure-regulators, their construc- 
tion, 78 

Pressures, high, in producer-gas en- 
gines, 154 

Preheaters, 229 

Producer, assembling, 253 

Producer, Henier, 216 

Producer, Henz, 228, 239, 240 

Producer, Bollinckx, 206, 220, 225, 
228, 234, 239 

Producer, Chavanon, 229 

Producer, cleaning of, 261 

Producer, Dawson, 174 

Producer, Dcschamps, 198 

Producer, Deutz, 206, 220, 224, 225, 
228, 229, 240 

Producer, Deutz, 231, 232 

Producer, Deutz lignite, 188 

Producer, Duff, 195 

Producer, Fange-Chavanon, 198 

Producer, Fichet-Heurty, 240, 245 
Producer, Gardie, 183 
Producer-gas, 153 
Producer-gas, 165 
Producer-gas as a furnace fuel, 177 
Producer-gas, calorific value of, 200 
Producer-gas, composition of, 106 
.Producer-gas plants, tests of, 297 
Producer-gas, writers on, 154 
Producer, general arrangement of 

suction, 204 
Producer, Goebels, 206 
Producer, Hille, 206, 23Q 
Producer, Kiderlen, 206 
Producer, Kiderlen, 216 
Producer, Koerting, 2^2 
Producer, Lencauchez, 212, 214 
Producer, Phoenix, 217 
Producer, Pierson, 224, 22Q 
Producer, Pintsch, 206, 216, 224, 231, 

232, 239, 245, 248 
Producer, Riche", 168, 100, 193. 195, 

Producer (see also Generator) 
Producer, stopjKige of, 261 
Producer, Taylor, 206, 214, 225, 231, 

Producer, test by smoke, 254 
Producer, test of Deutz, 298 
Producer, test of Dowson, 296 
Producer, tests of Winterthur, 297 
Producer, Thwaite, 195 
Producer, Wiedenfeld, 206, 216, 220, 

225, 234, 239 
Producer, Winterthur, 225, 228, 236 
Producers, advantages of suction, 

Producers, combustion, 103 
Producers, conditions of j)erfect oper- 
ation, 251 
Producers, consumption of suction, 

Producers, distilling, 190 
Producers, efficiency of, 201 
Producers, efficiency of lignite, 190 
Producers, efficiency of wood, 194 
Producers, lignite, 188 
Producers, maintenance of, 254 
Producers, peat, 18S 
Producers, pressure, 174 
Producers, self -reducing, 193 
Producers, sj)eci fixations of, 281 
Producers, suction, 199 



Producers, suction (see also Suction- 
producers | 
Producers, tests of, 297 
Producers with external vaporizers, 

Production of gas, 173 

Pulley, disconnection of, in stopping 

engine, 132 
Pump, circulating with by-pass, 106 
Purifier, filler, 185 
Purifier, Fichct-Heurtey, 345 
Purifier, material for, 245 
Purifier, moss, 185 
Purifier, PinLsch, 245 
Purifier, sawdust, 185 
Purifiers for gas, 184 
Purifiers for producer-gas, 244 

Recorder, analysis of inertia of ex- 
plosion, 277 

Recorder, explosion, for industrial en- 
gines, 185 

Recorder, the continuous explosion, 

Records of engines, 284 

Records of explosions, 388 

Records, indicator, 127 

Rcgrinding of valves, 122 

Regularity, cyclic, 48, 53 

Remagnetizalion of magnetos, 33 

Resuscitation after asphyxiation, i7r 

Retort, cleaning of, 225 

Retort of producer, 190 

Retort, support, 214 

Revolutions, variations in number of, 

Rollers, 51 

Running, steadiness of, 52 

Sand for foundation, 87 

Sawdust in producers, 193 

Scavenging, 142, 155 

Scrubber, 189, 199 

Scrubber, combined with gas-holder, 

Scrubber for producer-gas, 240 
Scrubber, size of, 253 
Selection of gas-engine, 21 

^having-; in producers, rQ3 

Slide-valve for charging-box, 223 

Slide-valve, its disadvantages, 23 

Sluice-valves, 101 

Smoke from cylinder, 149 

Spark-plug, 32 

S|Kvili<;uii>ns of engines, 281 

Specifications of producers, 281 

S[n'C(l, how to increase, 124 

Speed of oil-engines, 264 

Speed of volatile hydrocarbon en- 
gines, 264 

Speed, variation of, with load, 52 

Spokes of fly-wheels, 49 

Spring for valves (see Valves) 

Springs, selection of, for explosion- 
recorder, 277 

Starter, Tangyc, 65 

Starting an engine, 128 

Starting, automatic, 63, 130 

Starting by compressed air, 64 

Starting by hand, 63 

Starting by hand-pumps, 64 

Starting, difficulties in, 134 

Starting, how accomplished, 66 

Starting of producer-gas engine, 258 

Steadiness, 52 

Steam-engine, cost of installation, 19 

Steam-engine, cost of operation, 19 

Stoppage of producer, 261 

Slopping the engine, 132 

Stops, sudden, 151 

Straw in producers, 193, 254 

Street -gas, 165 

Suction, determination of resistance 
to, 274 

Suction, noises caused by, mi 

Suction of air, 81 

Suction period, 21 

Suction -producer, general arrange- 

Sucti on -producers, 199 
Suction -producers, advantages of, 199 
Suction -producers, efficiency of, 201 
Suction -valve, leakage of, 142 
Superheater, Wimerthur, 236 
Sylvester treatment, 171 

Tanks, connection of, 105 
Tanks, design of, :o3 



Tanks, location of, 102 

Tanks for water-jacket, how mounted, 

Tar in producer-plants, 200 

Tar, removal of, 250 

Tar (see also Scrubber, Purifier, etc.) 

Taylor, A., 199 

Terminals of magneto apparatus, 34 

Tests of gas-engine plants, 283 

Tests of high-speed engines, 268 

Tests of producer-gas engines, 297 

Thrust-bearings, 51 

Tongue, traction of, in asphyxiation 
cases, 172 

Tower, washer, 244 

Town -gas (see Street -gas) 

Tree branches for coolers, 107 

Trepidations, 92 

Tube, gas-supply pipe of incandes- 
cent, 77 

Tube, incandescent, 27 

Tube, incandescent, adjustment of, 

Tube, incandescent, breakage of, 137 
Tube, incandescent, danger of break- 
ing, 131 
Tube, incandescent, how started, 

Tube, incandescent, leakage of, 138 
Tubes as vaporizers, 231 
Tubes, incandescent, 28, 159 
Tubes, incandescent, valved, 29 
Tubes, use of special valves with in- 
candescent, 29 
Tubes, valveless ignition, 28 

Valve-chests, 124 

Valve mechanism, slide, 23 

Valvc-regrinding, 122, 135 

Valve-stem lubrication, 119 

Valves, 122 

Valves, accessibility of, 25 

Valves, cooling of, 25 

Valves, cooling of, in high-pressure 

engines, 156 
Valves, defective operation of, 135 
Valves, free, 27 

Valves, mechanical control of, 27 
Valves, modern, 24 
Valves, necessity of cleanliness, 25 

Valves, regulation of, before starting, 

Valves, requisites of, 25 
Valves, retardation in action of, 146 
Vaporizer, Bollinckx, 234 
Vaporizer, Chavanon, 229, 234 
Vaporizer, Deutz, 231, 232, 229, 225 
Vaporizer, Field, 233 
Vaporizer, internal, 206 
Vaporizer, Koerting, 232 
Vaporizer, maintenance of, 255 
Vaporizer, operation of, 234 
Vaporizer, Pierson, 229 
Vaporizer, Pintsch, 231, 232 
Vaporizer-preheaters, 229 
Vaporizer, size of, 253 
Vaporizer, Taylor, 231, 232 
Vaporizer, Wiedenfeld, 225, 234 
Vaporizers, external, 206, 230 
Vaporizers, internal, 229 
Vaporizers, partition, 234 
Vaporizers, regulation of, 236 
Vaporizers, tubular, 231 
Ventilation in engine-room, 69 
Vibration, 89 
Vibration of air, 92 
Vibration, prevention of, 89, 90 


Water circulation, 98, 107, 125 

Water circulation by pump, 107 

Water circulation, care during opera- 
tion, 132 

Water circulation, how effected, 102 

Water circulation, prevention of 
freezing, 133 

Water-coolers, 106 

Water-coolers, size of, 109 

Water for circulation, 99 

Water for producer-gas engines, 203 

Water-gas, 153, 167 

Water in cylinder, 136 

Water in exhaust, 136 

Water-jacket, 41, 98, 125, 157 

Water-jacket, incrustation of, 148 

Water-jacket, outlet of, 98 

Water-jacket, prevention of incrus- 
tation, 107 

Water-pipe, 102 

Water, purification of, for circulation,. 



Water, running, for jacket, 98 

Water-tanks, 101 

Water-tanks, connection of, 103, 105 

Water-tanks, design of, 103 

Water-tanks, location of, 102 

Washer, Benz, 240 

Washer, combined with gas-holder, 

Washer, Deutz, 240 
Washer, Fichet-Heurtey, 240 
Washer for gas, 199 
Washer for producer-gas, 240 

Washer, maintenance of, 256 
Washer, material employed in, 242 
Washer, Winterthur, 240 
Washers, 184 
Wear, premature, 146 
Witz apparatus, 284 
Wood as fuel, 254 
Wood, calorific value, 194 
Wood-gas, 153, 168 
Wood-gas, purification of, 195 
Wood in producers, 190, 192, 193 
Work, definition of effective, 60 


Oil Engine 

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Air Compressors, Generator Sets, 
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